Labyrinthopeptins as anti-viral agents

ABSTRACT

The present invention relates to novel labyrinthopeptin derivatives. These labyrinthopeptin derivatives are useful for the treatment of infectious diseases, such as an infectious disease caused by an infection with human respiratory syncytial virus (RSV), Kaposi sarcoma-associated herpesvirus (KSHV), cytomegalovirus (CMV/HCMV), dengue virus (DENV), chikungunya virus (CHIKV), tick-borne encephalitis virus (TBEV; FSME virus), vesicular stomatitis Indiana virus (VSV), zika virus (ZIKV) and/or hepatitis C virus (HCV). Said labyrinthopeptin derivatives are also useful for analyzing the mode of action of labyrinthopeptins. Also encompassed by the present invention are labyrinthopeptins for use in treating an infectious disease, in particular an infectious disease caused by an infection with any one of the viruses selected from RSV, KSHV, CMV, CHIKV, TBEV, VSV, ZIKV and HCV. The invention further relates to a combination of labyrinthopeptin A1 and A2 for use as a medicament, e.g. for treating an infectious disease caused by an infection with RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/or HCV.

The present invention relates to novel labyrinthopeptin derivatives.These labyrinthopeptin derivatives are useful for the treatment ofinfectious diseases, such as an infectious disease caused by aninfection with human respiratory syncytial virus (RSV), Kaposisarcoma-associated herpesvirus (KSHV), cytomegalovirus (CMV), denguevirus (DENV), chikungunya virus (CHIKV), tick-borne encephalitis virus(TBEV; FSME virus), vesicular stomatitis Indiana virus (VSV), zika virus(ZIKV) and/or hepatitis C virus (HCV). Said labyrinthopeptin derivativesare also useful for analyzing the mode of action of labyrinthopeptins.Also encompassed by the present invention are labyrinthopeptins for usein treating an infectious disease, in particular an infectious diseasecaused by an infection with any one of the viruses selected from RSV,KSHV, CMV, CHIKV, TBEV, VSV, ZIKV and HCV. The invention further relatesto a combination of labyrinthopeptin A1 and A2 for use as a medicament,e.g. for treating an infectious disease caused by an infection with RSV,KSHV, CMV, DENV CHIKV, TBEV, VSV, ZIKV and/or HCV.

Lantibiotics are peptides that are ribosomally synthesized from bacteriasuch as staphylococci, lactobacilli, and actinomycetes. The commonstructural characteristic of lantibiotics is the noncanonical amino acidlanthionine, which confers conformational stability to the peptide. Thelabyrinthopeptins are new class of carbacyclic lantibiotics and havebeen identified in 1988 in Actinomadura namibiensis (Drug Discovery fromNatural Products, Kap. 3, S. 49ff). They are representatives of a newtype of lantibiotics with a unique carbacyclic post-translationallymodified amino acid named labionin. The chemical structure of labioninis shown in FIG. 1(B).

The structure of the labyrinthopeptins was published in 2008(WO2008/040469 and Meindl, 2010, Angew. Chem. Int. Ed. 49, 1151-1154).Labyrinthopeptins, particularly Labyrinthopeptin A1 (also called LabA1or LabyA1) and Labyrinthopeptin A2 (also called LabA2 or LabyA2) haveseveral interesting biological activities. For example, LabyA2 shows anexcellent efficacy against neuropathic pain in the mouse model. LabyA1was recently shown to inhibit both HIV and HSV at sub-micromolarconcentrations in vitro (Férir 2013, PLOS one, 8(5):e64010). Thecompound is suggested to block viral entry by interacting with viralenvelopes and to prevent cell-to-cell transmission (Meyerhans, 2015,Nat. Prod. Rep., 2015, 32, 29-48). Although LabyA1 is effective againstresistant HIV and HSV viruses, it does not cause an inflammatoryresponse in peripheral blood mononuclear cells (PBMCs). Also anti-viralactivity of LabyA1 against Dengue virus (DENV) has been described(Dominique Schols, HVBD meeting 2013). Identifying the mode of action oflabyrinthopeptins may pave the way for the identification of further(infectious) diseases that can be treated with these molecules.

Viral infections are still a global problem, causing several milliondeaths each year. For example, 1-3% of the population of North Americaand Europe, and up to 50% of the population in some areas of equatorialAfrica has or had an infection with the Kaposi sarcoma-associatedherpesvirus (KSHV, also called human herpesvirus 8, HHV8, or KS agent).In addition, it was shown that about 4% of breast cancer patients inTaiwan are KSHV-infected. Human cytomegalovirus (CMV, also called HCMV)is found throughout all geographic locations and socioeconomic groups,and infects between 60% and 70% of adults in industrialized countriesand almost 100% in emerging countries. A CMV infection is typicallyunnoticed in healthy people, but can be life-threatening for theimmunocompromised, such as HIV-infected persons, organ transplantrecipients, or newborn infants. After infection, CMV remains latentwithin the body throughout life and can be reactivated at any time.Eventually, it may cause mucoepidermoid carcinoma and possibly othermalignancies such as prostate cancer.

The Dengue virus (DENV) causes a wide range of diseases in humans, froma self limited Dengue Fever (DF) to a life-threatening syndrome calledDengue Hemorrhagic Fever (DHF) or Dengue Shock Syndrome (DSS). Therecurrently is no human vaccine against DENV available.

Furthermore, the Lancet (2015) and the Center for Disease Control andPrevention (CDC) announced that the Human respiratory syncytial virus(RSV, also called hRSV) is a major cause of morbidity and mortality ofchildren under 5 years and represents a major problem in elderly andimmunocompromised patients. About 70% of children are infected prior totheir first birthday. At the age of 2 years, nearly every child had anRSV infection. The mortality rate is relatively low, however, RSV can bedangerous for children under 2 at risk as well as for older patients.Indeed, according to the CDC, around 14,000 mostly elderly patients diedin the US due to an RSV infection in 2014. There is currently noeffective treatment for RSV infections of the lower respiratory tract(lower respiratory tract infection, LRTI). There are a few drugs whichare approved for seasonal prophylactic treatment of RSV or for theprevention of RSV infection. However, some of these medicaments havesignificant side effects.

Chikungunya-virus (CHIKV) is a pathogenic RNA virus transmitted viabites by Aedes mosquito vectors. It causes fever, polyarthralgia, rashand is usually cleared after a short symptomatic period. However,chronification of symptoms occurs in a subset of symptomatic patients,causing painful and debilitating, inflammatory arthralgia, accompaniedby disability, fatigue and depression. Recent and ongoing outbreaks,facilitated by globalization and expanded vector usage have raisedscientific and public health attention. There is neither a specificantiviral treatment nor a protective vaccine available.

Tick-borne encephalitis virus (TBEV) is the virus associated withtick-borne encephalitis (TBE). TBE is a viral infectious diseaseinvolving the central nervous system. The disease most often manifestsas meningitis, encephalitis, or meningoencephalitis. Although TBE ismost commonly recognized as a neurological disorder, mild fever can alsooccur. Long-lasting or permanent neuropsychiatric sequelae are observedin 10 to 20% of infected patients. The number of reported cases has beenincreasing in most countries. The disease is incurable once manifested,so there is no specific drug therapy for TBE. Symptomatic brain damagerequires hospitalization and supportive care based on syndrome severity.

Zika virus (ZIKV) causes Zika fever. Zika virus has a nonsegmented,single-stranded, positive-sense RNA genome and is spread by Aedesmosquitoes. Zika virus is related to dengue fever, yellow fever,Japanese encephalitis, and West Nile viruses. Zika fever (also known asZika virus disease) has often no symptoms, but when present the symptomsare usually mild and can resemble dengue fever. The symptoms may includefever, red eyes, joint pain, headache, and a maculopapular rash.However, infections in pregnant women may also infect the baby and havebeen linked to miscarriage and microcephaly. There is no effectivevaccine against Zika fever.

Vesicular stomatitis Indiana virus (VSV) is a pathogenic RNA-virus thatinfects insects, cattle, horses and pigs. VSV is zoonotic causingflu-like symptoms in humans. The virus is transferred by insects. Thereis no specific treatment available.

The hepatitis C virus (HCV) causes hepatitis C which is an infectiousdisease that primarily affects the liver. The virus persists in theliver in about 75% to 85% of those initially infected. Chronic HCVinfection often leads to liver disease and occasionally to cirrhosis.Cirrhosis can be the cause for the development of liver failure, livercancer, or esophageal and gastric varices. Globally, between 130-150million people have chronic hepatitis C infection (“Hepatitis C Factsheet No 164”, WHO, July 2015, Retrieved 4 Feb. 2016). At present thereis no vaccine against hepatitis C available.

Thus, there is a need for finding further anti-viral drugs, particularlyfor the treatment and/or prevention of infectious diseases arising froman infection with KSHV, CMV, RSV, DENV, CHIKV, TBEV, VSV, ZIKV and/orHCV. In addition, there is also a need for novel means and methods tounravel the mode of action of labyrinthopeptins.

Thus, the technical problem underlying the present invention is theprovision of means and methods for the treatment and/or prevention ofviral infections, particularly for the treatment and/or prevention ofinfections with KSHV, CMV, RSV, DENV, CHIKV, TBEV, VSV, ZIKV and/or HCV;and the provision of means and methods for analyzing the mode of actionof labyrinthopeptins.

The technical problem is solved by provision of the embodiments ascharacterized in the claims.

Accordingly, the present invention relates to a peptide (i.e. alabyrinthopeptin derivative) comprising or consisting of the amino acidsequence

wherein

-   Lab is labionin-   X₁ is an amino acid selected from Asn, Asp, and Glu;-   X₂ is an amino acid selected form Ala, Trp, and Ser;-   X₃ is an amino acid selected from Val, Leu, and Ile;-   X₄ is an amino acid selected from Trp and Tyr;-   X₅ is an amino acid selected from Glu and Asp;-   X₆ is an amino acid selected from Thr and Ser;-   X₇ is an amino acid selected from Gly and Pro;-   X₈ consists of a sequence of 3 to 5 amino acids;-   R₁ is selected from H, a (C₂-C₁₂)alkynyl, a C(O)—(C₂-C₁₂)alkynyl, a    C(O)—O—(C₂-C₁₂)alkynyl, and a C(O)NH—(C₂-C₁₂)alkynyl; wherein R₁    carries the alkynyl group at the terminal position; and-   R₂ is selected from H, a [C(O)]—NH—(C₂-C₁₂)alkynyl or a    [C(O)]—O—(C₂-C₁₂)alkynyl; wherein the moiety [C(O)] is the carbonyl    group of the terminal amino acid; wherein R₂ carries the alkynyl    group at the terminal position;    wherein if R₁ is H, then R₂ is not H.

The present invention solves the above identified technical problemsince, as documented herein below and in the appended Examples,labyrinthopeptin derivatives that can be further derivatized withcompounds such as anti-viral drugs or marker molecules have beenobtained. These labyrinthopeptin derivatives enable a more efficientanti-viral treatment (e.g. by linkage to anti-viral drugs) and alsoenable a more detailed analysis of the mode of action oflabyrinthopeptins (e.g. by linkage to marker molecules). As mentionedabove, understanding the mode of action of labyrinthopeptins would pavethe way to the development of further effective anti-viral drugs.

The labyrinthopeptin derivative of the present invention has anti-viralactivity, particularly against RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV,ZIKV and/or HCV, preferably against DENV.

Assays for testing the anti-viral activity of compounds such aslabyrinthopeptins are commonly known in the art. For example, to testfor the anti-viral activity of the labyrinthopeptin derivative of theinvention, the labyrinthopeptin derivative may be added to cells (e.g.Huh-7.5 cells). Then, the cells may be infected with the virus to betested (e.g. RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/or HCV,preferably DENV). The amount of virus-positive cells may be evaluated byimmunocytochemistry. For example, a primary antibody directed againstthe virus and a secondary antibody that has a conjugated fluorophore maybe applied. The number of total cells may be determined by countingDAPI-stained nuclei. Thus, the percentage of virus-positive cells may becalculated. The obtained result is preferably compared to non-infectedcells.

In more detail, to test for the anti-viral activity oflabyrinthopeptins, labyrinthopeptin derivatives or combinations oflabyrinthopeptins/labyrinthopeptin derivatives, Huh-7.5 cells (e.g. 3×

10

̂4 per well) may be seeded in black 96-well optical-bottom plates [Nunc]in full growth medium one day prior to infection. After washing withPBS, 40 μl assay medium (5% FBS) may be added to cells containing thelabyrinthopeptin of the invention, the labyrinthopeptin derivative ofthe invention (final conc. 50, 16.7, 5.56, 1.85, 0.62, 0.21, 0.069μg/ml) or a combination of labyrinthopeptins/labyrinthopeptinderivatives (25, 8.3, 2.8, 0.93, 0.31, 0.10, 0.034 μg/ml each).Treatments are preferably run in doublets. PBS serves as a control.After 30 min of incubation, cells may be infected with the virus, (e.g.RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV, and/or HCV, preferablyDENV, e.g. DENV Type 2 New Guinea C) at an MOI of 0.5 to give a finalvolume of 60 μl/well. After 2 h incubation at room temperature cells maybe washed with PBS and 100 μl assay medium may be added per well.Infected cells may be incubated for another 48 h. Hereafter, media maybe removed from the wells and cells may be fixed with 4% PFA. Fixedcells may be washed extensively with PBS and permeabilized with 0.25%TritonX-100 for 5 min. After blocking with 5% FBS in PBS, primaryantibody directed against the virus may be applied (e.g. Anti-DengueVirus E glycoprotein antibody [DE1] (ab41349) [Abcam], 1:100 diluted in5% FBS/PBS) for 2 h. After washing, secondary antibody (e.g. AlexaFluor® 488 Goat Anti-Mouse IgG (H+L) [Life Technologies], 1:1000 dilutedin 5% FBS/PBS) may be applied for 1 h. Finally, cells may be stainedwith DAPI (500 ng/ml in PBS) for 5 min.

Fluorescent cells can be analyzed by high-content imaging using theautomated microscope ImageXpressMicro [Molecular Devices] and theMetaXpress-software. The excitation wavelengths may be set to 360 nm(DAPI) and 485 nm (Alexa Fluor488) and the emission wavelengths may beset to 460 nm (DAPI) and 516 nm (Alexa Fluor488). Images of sixsites/well may be acquired (2 columns, 89 μm spacing; 3 rows, 67 μmspacing). The number of total cells/site may be determined byautomatically counting DAPI-stained nuclei. The percentage ofvirus-positive cells (e.g. DENV-positive cells) may be calculated byautomatically evaluating the number of Alexa Fluor 488-positive cells inrelation to the total cell number. Values obtained from the six sitesmay be averaged and plotted onto a semi-logarithmic X/Y-chart.IC₅₀-values may be calculated by non-linear regression.

As described above, if in the labyrinthopeptin derivative of the presentinvention R₁ or R₂ is an alkynyl, then the alkynyl group is at theterminal position. As described above, R₁ may be an urea derivative(i.e. C(O)NH—(C₂-C₁₂)alkynyl) and/or R₂ may be an amide (i.e.[C(O)]—NH—(C₂-C₁₂)alkynyl) or an ester (i.e. [C(O)]—O—(C₂-C₁₂)alkynyl).Preferably, R₂ is H and R₁ carries one of the alkynyl-compoundsmentioned above for R₁. Thus, preferably, R₂ is H and R₁ is analkynyl-compound selected from the group consisting of a(C₂-C₁₂)alkynyl, a C(O)—(C₂-C₁₂)alkynyl, a C(O)—O—(C₂-C₁₂)alkynyl, and aC(O)NH—(C₂-C₁₂)alkynyl. More preferably, R₂ is H and R₁ is aC(O)—(C₂-C₁₂)alkynyl. Most preferably, R₂ is H and R₁ is hex-5ynoyl. Asmentioned, if R₁ is an alkynyl, then the alkynyl group is at theterminal position.

The labyrinthopeptin derivative of the present invention has a terminalalkyne group (i.e. alkynyl group). Thus, the labyrinthopeptin derivativeof the invention may be further derivatized with an azide via dipolarcycloaddition, particularly via “Azide-Alkyne Huisgen Cycloaddition”(Huisgen, 1961, Proceedings of the Chemical Society of London, 357).Thus, the present invention relates to the labyrinthopeptin derivativeof the present invention, wherein R₁ and/or R₂ is/are derivatized withan azide-labeled compound. Said compound may be a compound selected froman anti-viral drug or a marker molecule.

Anti-viral drugs that are linked to the labyrinthopeptin derivative asdescribed above may further enhance the anti-viral activity of thelabyrinthopeptin derivative. For example, suitable anti-viral drugs thatmay be used as compound in the azide-labeled compound are acyclovirpenciclovir, Zidovudine, brivudin, cidofovir, HDVD (L-dioxolane uracilanalog), Idoxuridin, Famciclovir, Sorivudin, Valaciclovir, Cidofovir,Brincidofovir, Ganciclovir, Valganciclovir, Foscarnet, Maribavir, CMVIG,Letermovir, Leflunomide (antimetabolite, used as a disease-modifyingagent in rheumatoid arthritis, has also been successfully used off-labelin both CMV disease treatment and prophylaxis), RSV604 (Challa, 2015,Antimicrob Agents Chemother 59(2): 1080-7), ALS-8176 (Challa, 2015,Antimicrob Agents Chemother 59(2): 1080-7), GS-5806 (Gilead®), or asmall molecule inhibitor (DeVincenzo, 2014, Proc Natl Acad Sci USA107(19): 8800-5.). The anti-viral drug may also be NITD-008 orBalapiravir.

By linking a marker molecule to the herein provided labyrinthopeptinderivative (via dipolar cycloaddition) the mode of action oflabyrinthopeptins may be analyzed. For example, by linking thelabyrinthopeptin derivative to a marker molecule, the location oflabyrinthopeptins within the infected cell and/or the interactionbetween labyrinthopeptins and virus particles may be analyzed.Therefore, imaging methods such as fluorescence microscopy,chemifluorescence microscopy, chemiluminescence microscopy, electronmicroscopy, nuclear magnetic resonance-based systems orradioisotope-based systems may be used.

Suitable marker molecules that may be used as compound in theazide-labeled compound are described in the following. In particular,herein the terms “marker molecule(s)” or “marker(s)” are usedinterchangeably and refer to a label or marker that is preferablycapable of producing, either directly or indirectly, a detectablesignal. For example, the marker molecule may be a radioisotope, afluorophore or chemiluminescent (chromophore) compound, an enzyme, animaging agent, a magnetic or paramagnetic label, or a metal ion. Theterm “marker molecule(s)” includes fluorophores. The term “fluorophore”comprises compounds selected from the group consisting of adimethylaminocoumarin derivative, preferably7-dimethylaminocoumarin-4-acetic acid succinimidyl ester, dansyl,5/6-carboxyfluorescein and tetramethylrhodamine, BODIPY-493/503,BODIPY-FL, BODIPY-TMR, BODIPY-TMR-X, BODIPY-TR-X, BODIPY630/550-X,BODIPY-650/665-X, Alexa 350, Alexa 488, Alexa 532, Alexa 546, Alexa 555,Alexa 635, Alexa 647, Cyanine 3 (Cy 3), Cyanine 3B (Cy 3B), Cyanine 5(Cy 5), Cyanine 5.5 (Cy 5.5), Cyanine 7 (Cy 7), Cyanine 7.5 (Cy 7.5),ATTO 488, ATTO 532, ATTO 600, ATTO 655, DY-505, DY-547, DY-632, DY-647;fluorescent proteins, such as green fluorescent protein (GFP) andmodifications of GFP that have different absorption/emission properties.Herein a “marker molecule” may also be a complex of certain rare earthmetals (e.g., europium, samarium, terbium or dysprosium), as thesecomplexes can be used as fluorescent nanocrystals (quantum dots). Morepreferably, the “marker molecule” is a fluorophore selected from thegroup consisting of a dimethylaminocoumarin derivative, preferably7-dimethylaminocoumarin-4-acetic acid succinimidyl ester, dansyl,5/6-carboxyfluorescein and tetramethylrhodamine, BODIPY-493/503,BODIPY-FL, BODIPY-TMR, BODIPY-TMR-X, BODIPY-TR-X, BODIPY630/550-X,BODIPY-650/665-X, Alexa 350, Alexa 488, Alexa 532, Alexa 546, Alexa 555,Alexa 635, Alexa 647, Cyanine 3 (Cy 3), Cyanine 3B (Cy 3B), Cyanine 5(Cy 5), Cyanine 5.5 (Cy 5.5), Cyanine 7 (Cy 7), Cyanine 7.5 (Cy 7.5),ATTO 488, ATTO 532, ATTO 600, ATTO 655, DY-505, DY-547, DY-632, andDY-647. Preferred examples of optical imaging moieties are the cyaninedyes out of the group consisting of Carbacyanines, Oxacyanines,Thiacyanines and Azacyanines. Cyanine dyes are compounds defined by apolyene chain containing an odd number of carbon atoms linked byalternating single and multiple, preferably double, carbon-carbon bonds,terminated at either end by an amino group, one of which is quaternised.The cyanine and analogues aryl-linker-aryl chromophores optionally carrypendant or fused ring substituents. The cyanine dyes are particularlyuseful due to the wide range of spectral properties and structuralvariations available. A range of cyanine dyes are well known and tested,they have low toxicity, and are commercially available. The cyanine dyesare a single family of highly intense dyes with good aqueous solubility.They are pH insensitive between pH 3-10, exhibit low non-specificbinding, and are more photostable than fluorescein.

Herein the “marker molecule” that is used in the azide-labeled compoundmay also be a radioactive marker. Examples for radioisotopes that aresuitable for diagnostic radiopharmaceuticals are given in the following.Radioisotopes that can be use for positron emission tomography (PET)are, e.g., 18F, 11C, 64Cu, 13N, 15O, or 68Ga. Radioisotopes that can beused for gamma ray/photon (SPECT/scintigraphy) are, e.g., 99mTc, 123I,125I, 131I, 111In, 57Co, 153Sm, 133Xe, 51Cr, 81mKr, 201Tl, 67Ga, or75Se. For mass cytometry, metal based markers may be used. Theradioisotope markers (particularly the metals described above) could beattached to the azide containing rest, e.g., by using metal chelators(for example DOTA or NOGADA moieties).

In context of the invention the “compound” of the azide-labeled compoundmay also be an antibody, e.g. an antibody directing the labyrinthopeptinderivative of the invention to a particular cell, tissue or organ. Forexample, the antibody my direct the labyrinthopeptin derivative to theliver (e.g. to hepatocytes). For the treatment of a DENV infection, theantibody may direct the labyrinthopeptin derivative to cells of theimmune system (e.g. to T-cells or Langerhans dendritic cells). For thetreatment of an infection with Herpesviridae the antibody may direct thelabyrinthopeptin derivative to nerve cells (e.g. to oligodendrocytes orneurons). For the treatment of an infection with RSV the antibody maydirect the labyrinthopeptin derivative to the lung (e.g. to thealveolae). For the treatment of an infection with CHIKV the antibody maydirect the labyrinthopeptin derivative to muscle, joint or nerve tissue,e.g. addressing attachment factors such as TIM-1. For the treatment ofan infection with TBEV the antibody may direct the labyrinthopeptinderivative to cells of the central nervous tissue (brain, spinal cord).For the treatment of an infection with ZIKV the antibody may direct thelabyrinthopeptin derivative to subcutaneous tissue, the central nervoussystem, the skeletal muscles or the myocardium. For the treatment of aninfection with HCV the antibody my direct the labyrinthopeptinderivative to the liver (e.g. to hepatocytes).

The appended Examples show derivatization of LabyA1 and LabyA2 withazide-labeled Biotin. Thus, in a preferred aspect of the presentinvention, the azide-labeled compound is azide-labeled Biotin.

Thus, the present invention provides a labyrinthopeptin derivative,wherein via dipolar cycloaddition between the terminal alkynyl group ofR₁ and/or R₂ and an azide-labeled compound, said compound is added toobtain R₁′ and/or R₂′. Or, in other words, according to the invention acompound can be added to the labyrinthopeptin derivative via dipolarcycloaddition. This dipolar cycloaddition takes place between theterminal alkynyl group of R₁ and/or R₂ and the azide group of theazide-labeled compound. This dipolar cycloaddition converts R₁ to R₁′and/or R₂ to R₂′. An overview of potential R₁ and R₂ as well as thecorresponding R₁′ and R₂′ is given below.

As described above, R₁ may be a (C₂-C₁₂)alkynyl, a C(O)—(C₂-C₁₂)alkynyl,a C(O)—O—(C₂-C₁₂)alkynyl, or a C(O)NH—(C₂-C₁₂)alkynyl, wherein R₁carries the alkynyl group at the terminal position. As also describedabove, R₂ may be [C(O)]—NH—(C₂-C₁₂)alkynyl or a[C(O)]—O—(C₂-C₁₂)alkynyl, wherein [CO] is the carbonyl group of theterminal amino acid, and wherein R₂ carries the alkynyl group at theterminal position.

The R₁′ and R₂′ groups that correspond to these R₁ and R₂ groups,respectively, are shown in Tables 1 and 2, below.

TABLE 1 Potential R₁ groups and the corresponding R₁′ groups. R₁ R₁′(C₂)alkynyl (i.e. ethynyl) triazole-compound* (C₃—C₁₂)alkynyl(C₁—C₁₀)alkyl-triazole-compound* C(O)—(C₂)alkynylC(O)-triazole-compound* (i.e. C(O)ethynyl) C(O)—(C₃—C₁₂)alkynylC(O)—(C₁—C₁₀)alkyl-triazole- compound* C(O)—O—(C₂)alkynylC(O)—O-triazole-compound* (i.e. C(O)—O-ethynyl) C(O)—O—(C₃—C₁₂)alkynylC(O)—O—(C₁—C₁₀)alkyl-triazole- compound* C(O)NH—(C₂)alkynylC(O)NH-triazole-compound* (i.e. C(O)NH-ethynyl) C(O)NH—(C₃—C₁₂)alkynylC(O)NH—(C₁—C₁₀)alkyl-triazole- compound* hex-5ynoylC(O)—(C₃)alkyl-triazole-compound* *Here the “compound” is the compoundthat was azide-labeled before it had reacted with the alkynyl group ofR₁. For example, said compound may be an anti-viral drug or a markermolecule.

TABLE 2 Potential R₂ groups and the corresponding R₂′ groups. R₂ R₂′ c[C(O)]—NH-triazole-compound* [C(O)]—NH—(C₃—C₁₂)alkynyl[C(O)]—NH—(C₁—C₁₀)alkyl-triazole- compound* [C(O)]—O—(C₂)alkynyl[C(O)]—O-triazole compound* (i.e. [C(O)]—O-ethynyl)[C(O)]—O—(C₃—C₁₂)alkynyl [C(O)]—O—(C₁—C₁₀)alkyl-triazole- compound**Here the “compound” is the compound that was azide-labeled before ithad reacted with the alkynyl group of R₂. For example, said compound maybe an anti-viral drug or a marker molecule.

Thus, in the labyrinthopeptin derivative of the present invention, adipolar cycloaddition between the terminal alkynyl group of R₁ and/or R₂and an azide-labeled compound may have occurred to give a triazole thatbinds the compound (e.g. the anti-viral drug or the marker molecule) toR₁ and/or R₂. Said compound may be any one of the anti-viral drugs ormarker molecules as described above. Thus, the present invention relatesto a labyrinthopeptin derivative (e.g. a derivative of LabyA1 orLabyA2), which comprises an anti-viral drug or a marker molecule. Or, inother words, the present invention relates to the herein providedlabyrinthopeptin derivative, which comprises R₁′ instead of R₁ and/orR₂′ instead of R₂. Preferably, said labyrinthopeptin derivativecomprises R₁′ instead of R₁ and R₂ is H.

The appended Examples demonstrate that the labyrinthopeptin derivativeof the present invention has anti-viral activity, e.g. against a DENVinfection. Thus, one aspect of the present invention relates to theherein provided labyrinthopeptin derivative for use as a medicament.Also encompassed by the present invention is a pharmaceuticalcomposition comprising the labyrinthopeptin derivative of the invention,wherein the pharmaceutical composition further comprises apharmaceutically acceptable carrier and/or diluent. The inventionfurther relates to the labyrinthopeptin derivative of the invention orthe pharmaceutical composition of the invention for use in treatingand/or preventing an infectious disease, particularly a viral infection.

Thus, the labyrinthopeptin derivative or the pharmaceutical compositionof the invention can be used for both, treating an existing viralinfection or preventing the occurrence of a viral invention. It ispreferred herein that the labyrinthopeptin derivative of the inventionor the pharmaceutical composition of the invention is used for treatingan existing viral infection. Said viral infection may be an infectionwith any one of the viruses selected from RSV, KSHV, CMV, DENV, CHIKV,TBEV, VSV, ZIKV and HCV, preferably DENV. Said infection (i.e. saidinfectious disease) may also be caused by a combination of infectionswith at least two of the viruses selected from RSV, KSHV, CMV, DENV,CHIKV, TBEV, VSV, ZIKV and HCV.

Accordingly, the present invention relates to a method of treatingand/or preventing an infection with any one of the viruses selected fromRSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV, and HCV, preferably DENV,wherein the method comprises administering an effective dose of thelabyrinthopeptin derivative of the present invention or of thepharmaceutical composition comprising said labyrinthopeptin derivativeto a subject in need of such a treatment.

For example, one aspect of the present invention relates to a method oftreating and/or preventing an infection with any one of the virusesselected from RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV and ZIKV,preferably DENV, wherein the method comprises administering an effectivedose of the labyrinthopeptin derivative of the present invention or ofthe pharmaceutical composition comprising said labyrinthopeptinderivative to a subject in need of such a treatment.

Herein a “viral infection” or “infection with a virus” means aninfectious disease, which is cause by an infection with a virus.

Anti-viral activity of LabyA1 and LabyA2 has been shown in the priorart. In particular, anti-viral activity of these substances againstmycovirus (RNA virus/Influenza A), herpes simplex virus 1 and 2,adenovirus (DNA virus), human immunodeficiency virus (HIV), Humanherpesvirus 6 (HHV-6) and Bovine viral diarrhea virus (BVDV) have beenshown (WO 2008/040469 A1; Férir 2013, PLOS one, 8(5):e64010; andMeyerhans, 2015, Nat. Prod. Rep., 2015, 32, 29-48). In addition, asdescribed above, activity of LabyA1 against HIV and DENV is known in theart. However, the prior art also discloses that the anti-viral effect oflabyrinthopeptins is highly virus-specific. In particular, Férir et al.(2013, PLOS one, 8(5):e64010) discloses that none of the testedlantibiotics showed antiviral activity against the influenza virusesH₁,N₁, H₃N₂ and the influenza B virus. In addition, this document showsdata demonstrating that LabyA1 interacts with the virus itself and notwith the CD4⁺ T cells. These data indicate that labyrinthopeptins actthrough a specific and direct interaction with particular selected virusspecies. In contrast, in context of the present invention it wassurprisingly found that LabyA1 and LabyA2 have a considerably highanti-viral activity against CMV, KSHV, RSV, TBEV, ZIKV and HCV, and thatLabyA1 has also a considerably high anti-viral activity against CHIKVand VSV. These viruses are completely different from all viruses forwhich activity has been shown in the prior art. RSV belongs to the viralfamily of Paramyxoviruses that is completely unrelated to all virusesfor which an activity of LabyA1 or LabyA2 has been shown in the priorart. CHIKV belongs to the family of Togaviridae; VSV belongs to thefamily of Rhabdoviridae; and HCV belongs to the family Flaviviridae.These families are also completely unrelated to the viruses for which anactivity of labyrinthopeptins has been shown in the prior art. As HSV(for which the anti-viral activity of LabyA1 and LabyA2 has already beendemonstrated) KSHV and CMV are representatives of the family of herpesviruses. However, KSHV and CMV have different biological andpathophysiological properties. HSV belongs to the subfamily ofAlphaherpesvirinae whose members are neurotropic (infect nervous systemtissue) and have a short reproductive cycle (˜18 hrs). Their primarytarget cells are in the mucoepithelium. They may persist in neurons. Incontrast, KSHV and CMV belong to the subfamilies of Gammaherpesvirinaeand Betaherpesvirinae, respectively. Betaherpesvirinae are lymphotropicand have a long reproductive cycle. They have a restricted host rangeand infected cells become enlarged (cytomegalo). Compared toAlphaherpesvirinae, they establish their latency in leucocytes, not inneurons. Gammaherpesvirinae are also lymphotropic and specific foreither T or B lymphocytes. Both, Gammaherpesvirinae andBetaherpesvirinae may be cancerogenic whereas Alphaherpesvirinae arenot. Labyrinthopeptins have been described as having a highly specificmode of action. Therefore, the finding that LabyA1 and LabyA2 haveanti-viral action on selected viruses that are completely different ascompared to the viruses for which anti-viral activity oflabyrinthopeptins has been described in the art is entirely unexpected.

Thus, another aspect of the present invention relates to a peptide (i.e.a labyrinthopeptin) for use in treating and/or preventing an infectionwith any one of the viruses selected from RSV, KSHV, CMV, CHIKV, TBEV,VSV, ZIKV and HCV wherein said peptide comprises or consists of theamino acid sequence

wherein

-   Lab is labionin-   X₁ is an amino acid selected from Asn, Asp, and Glu;-   X₂ is an amino acid selected form Ala, Trp, and Ser;-   X₃ is an amino acid selected from Val, Leu, and Ile;-   X₄ is an amino acid selected from Trp and Tyr;-   X₅ is an amino acid selected from Glu and Asp;-   X₆ is an amino acid selected from Thr and Ser;-   X₇ is an amino acid selected from Gly and Pro; and-   X₈ consists of a sequence of 3 to 5 amino acids.

The labyrinthopeptin of the present invention has anti-viral activity,particularly against RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/orHCV (e.g. against RSV, KSHV, CMV, CHIKV, TBEV, VSV and/or ZIKV),preferably against RSV, KSHV, CMV, CHIKV, TBEV, ZIKV and/or HCV; evenmore preferably against RSV, KSHV, CMV, ZIKV and/or HCV; even morepreferably against KSHV, CMV, ZIKV and/or HCV; even more preferablyagainst CMV and/or HCV; and most preferably against CMV.

The amino acid labionin (or Labionin) as well as their occurrence inlabyrinthopeptins is known in the art and described, e.g., in Häbich,Angew. Chem. Int. Ed., 2010, 49: 1151-1154. In particular, labionin isan amino acid that actually spans over three residues, in analogy tolanthionin (see FIG. 1). The C-alpha atom spans the bridges. Thestructure of labionin is shown in FIG. 1.

Another aspect of the present invention relates to a pharmaceuticalcomposition comprising the labyrinthopeptin of the present invention foruse in treating and/or preventing an infection with any one of theviruses selected from RSV, KSHV, CMV, CHIKV, TBEV, VSV, ZIKV and HCV,wherein the pharmaceutical composition further comprises apharmaceutically acceptable carrier and/or diluent. Thus, the presentinvention relates to a method of treating and/or preventing an infectionwith any one of the viruses selected from RSV, KSHV, CMV, CHIKV, TBEV,VSV, ZIKV and HCV, wherein the method comprises administering aneffective dose of the labyrinthopeptin of the present invention or ofthe pharmaceutical composition comprising said labyrinthopeptin to asubject in need of such a treatment. It is preferred herein that saidlabyrinthopeptin or said pharmaceutical composition is used for treatingan existing infectious disease caused by a viral infection with any oneof viruses selected from RSV, KSHV, CMV, CHIKV, TBEV, VSV, ZIKV and HCV,or an existing viral invention that is caused by a combination ofinfections with at least two of the viruses selected from RSV, KSHV,CMV, CHIKV, TBEV, VSV, ZIKV and HCV.

Preferably, the pharmaceutical composition or the treatment method isused for treating and/or preventing an infection with any one of theviruses selected from RSV, KSHV, CMV, CHIKV, TBEV, VSV, ZIKV and/or HCV(e.g. selected from RSV, KSHV, CMV, CHIKV, TBEV, VSV and/or ZIKV), morepreferably selected from RSV, KSHV, CMV, CHIKV, TBEV, ZIKV and/or HCV;even more preferably selected from RSV, KSHV, CMV, ZIKV and/or HCV; evenmore preferably selected from KSHV, CMV, ZIKV and/or HCV; even morepreferably selected from CMV and/or HCV; and most preferably CMV.

The labyrinthopeptin of the present invention or the labyrinthopeptinderivative of the present invention may have a length of maximal 50amino acids, more preferably of maximal 40 amino acids, and even morepreferably of maximal 30 amino acids. Thus, one aspect of the presentinvention relates to the herein provided labyrinthopeptin derivative,pharmaceutical composition comprising said labyrinthopeptin derivative,or to the herein provided method, wherein said peptide (i.e. saidlabyrinthopeptin derivative) has a length of maximal 30 amino acids.Analogously, the invention relates to the herein providedlabyrinthopeptin, to the herein provided pharmaceutical compositioncomprising said labyrinthopeptin, or to the herein provided method,wherein said peptide (i.e. said labyrinthopeptin) has a length ofmaximal 30 amino acids. It is even more preferred that thelabyrinthopeptin or the labyrinthopeptin derivative of the presentinvention has a length of maximal 25 amino acids. Most preferably, thelabyrinthopeptin or the labyrinthopeptin derivative of the presentinvention has 18-20 amino acids.

As mentioned above, in the labyrinthopeptin or labyrinthopeptinderivative of the present invention as shown in SEQ ID NOs: 1 and 2,respectively, X₈ consists of a sequence of 3 to 5 amino acids. Forexample, X₈ may consist of the amino acid sequence X₈₋₁ to X₈₋₅ as shownbelow:

-   X₈₋₁ is absent or an amino acid selected from Trp or Tyr;-   X₈₋₂ is an amino acid selected from Val, Leu and Ile;-   X₈₋₃ is absent or an amino acid selected from Pro and Gly;-   X₈₋₄ is an amino acid selected from Phe, Met, Leu and Tyr, and-   X₈₋₅ is an amino acid selected from dehydrobutyrine, Ala, Thr, Asn    and Ser.

Dehydrobutyrine (Dhb) (also called didehydrobutyrine) is a naturallyoccurring amino acid that is present in a range of peptides includingantimicrobial peptides of the lantibiotic family. In nature, thesite-specific introduction of dehydrobutyrine into peptide chains arisesdue to enzymatic post-translational modifications, in which a threonineresidue is dehydrated by phosphorylation followed by β-elimination. Thestructure of dehydrobutyrine as present in LabyA1 is shown in FIG. 2.

In an example of the herein provided labyrinthopeptin orlabyrinthopeptin derivative, X₈ consists of the amino acid sequenceTrp-Val-Pro-Phe-dehydrobutyrine. Alternatively, X₈ may consist of theamino acid sequence Leu-Phe-Ala.

One aspect of the present invention relates to the herein providedlabyrinthopeptin, labyrinthopeptin derivative, pharmaceuticalcompositions, or methods, wherein

-   X₁ is Asn or Asp;-   X₂ is Ala or Trp;-   X₃ is Val or Leu;-   X₄ is Trp;-   X₅ is Glu;-   X₆ is Thr;-   X₇ is Gly; and-   X₈ is an amino acid sequence consisting of the amino acid sequence    Trp-Val-Pro-Phe-dehydrobutyrine, or consisting of the amino acid    sequence Leu-Phe-Ala.

The labyrinthopeptin of the invention or labyrinthopeptin comprised inthe labyrinthopeptin derivative of the invention may comprise or consistof LabyA2. Thus, one aspect of the present invention relates to thelabyrinthopeptin provided herein, to the labyrinthopeptin derivativeprovided herein, to the pharmaceutical compositions provided herein, orto the methods provided herein wherein

-   X₁ is Asp;-   X₂ is Trp;-   X₃ is Leu;-   X₄ is Trp;-   X₅ is Glu;-   X₆ is Thr;-   X₇ is Gly; and-   X₈ is an amino acid sequence consisting of the amino acid sequence    Leu-Phe-Ala.

In a preferred aspect of the present invention the labyrinthopeptin ofthe invention is LabyA2, e.g. as shown in FIG. 4. More preferably, thelabyrinthopeptin of the invention is LabyA2 as shown in FIG. 3(B),having the stereochemistry of natural LabyA2. It is also preferred thatthe labyrinthopeptin derivative of the present invention comprisesLabyA2, e.g. as shown in FIG. 4. More preferably, the labyrinthopeptinderivative of the invention comprises LabyA2 as shown in FIG. 3(B),having the stereochemistry of natural LabyA2.

A preferred aspect of the invention relates to LabyA2 for use intreating and/or preventing an infection with any one of the virusesselected from RSV, KSHV, TBEV, VSV, CMV, ZIKV and HCV (e.g. selected froRSV, KSHV, TBEV, VSV, CMV and ZIKV), preferably selected from KSHV, CMV,ZIKV and HCV, more preferably selected from CMV, ZIKV and HCV, and evenmore preferably HCV.

However, it is more preferred that the labyrinthopeptin of the inventionor the labyrinthopeptin comprised in the labyrinthopeptin derivative ofthe invention comprises or consists of LabyA1. Thus, one aspect of thepresent invention relates to the labyrinthopeptin provided herein, tothe labyrinthopeptin derivative provided herein, to the pharmaceuticalcompositions provided herein, or to the methods provided herein wherein

-   X₁ is Asn;-   X₂ is Ala;-   X₃ is Val;-   X₄ is Trp;-   X₅ is Glu;-   X₆ is Thr;-   X₇ is Gly; and-   X₈ is an amino acid sequence consisting of the amino acid sequence    Trp-Val-Pro-Phe-dehydrobutyrine.

In an even more preferred aspect of the present invention thelabyrinthopeptin of the invention is LabyA1, e.g. as shown in FIG. 4.Even more preferably, the labyrinthopeptin of the invention is LabyA1 asshown in FIG. 3(A), having the stereochemistry of natural LabyA1. It isalso more preferred that the labyrinthopeptin derivative of the presentinvention comprises LabyA1, e.g. as shown in FIG. 4. Even morepreferably, the labyrinthopeptin derivative of the invention comprisesLabyA1 as shown in FIG. 3(A), having the stereochemistry of naturalLabyA1.

A preferred aspect of the invention relates to LabyA1 for use intreating and/or preventing an infection with any one of the virusesselected from RSV, KSHV, TBEV, CMV VSV, CHIKV, ZIKV and HCV (e.g.selected from RSV, KSHV, TBEV, CMV VSV, CHIKV and ZIKV), preferablyselected from RSV, KSHV, CMV, CHIKV, ZIKV and HCV, more preferablyselected from KSHV, CMV, CHIKV, ZIKV and HCV, even more preferablyselected from CMV, CHIKV and HCV.

In context of the invention it was surprisingly shown that theanti-viral activity of the combination of LabyA1 and LabyA2 wassignificantly higher than that of the individual molecules. Such asynergistic effect of a combination of LabyA1 and LabyA2 has never beendisclosed or suggested in the prior art. Quite to the contrary, due tothe lack of anti-HIV and only moderate anti-HSV activity, LabyA2 wasdescribed to be a less attractive candidate for further antiviralstudies (Férir 2013, PLOS one, 8(5):e64010). However, in context of thepresent invention it has surprisingly and unexpectedly been found thatin combination with LabyA1, LabyA2 results in a considerably highanti-viral activity. This synergistic effect was not foreseeable.

Thus, the present invention relates to a combination of at least twolabyrinthopeptins or labyrinthopeptin derivatives for use as amedicament. Particularly, one aspect of the present invention relates toa combination of (i) and (ii) for use as a medicament, wherein (i) and(ii) are:

-   (i) a labyrinthopeptin or labyrinthopeptin derivative of the present    invention having    -   X₁ is Asn;    -   X₂ is Ala;    -   X₃ is Val;    -   X₄ is Trp;    -   X₅ is Glu;    -   X₆ is Thr;    -   X₇ is Gly; and    -   X₈ is an amino acid sequence consisting of the amino acid        sequence Trp-Val-Pro-Phe-dehydrobutyrine; and-   (ii) a labyrinthopeptin or labyrinthopeptin derivative of the    present invention having    -   X₁ is Asp;    -   X₂ is Trp;    -   X₃ is Leu;    -   X₄ is Trp;    -   X₅ is Glu;    -   X₆ is Thr;    -   X₇ is Gly; and    -   X₈ is an amino acid sequence consisting of the amino acid        sequence Leu-Phe-Ala.

In context of the invention it was surprisingly shown that the antiviralactivity of the combination of LabyA1 and LabyA2 could even be increasedif the ratio of LabyA1 and LabyA2 is 1:1. Thus, the invention relates tothe herein provided combination, wherein the ratio of thelabyrinthopeptin/labyrinthopeptin derivative (i), and thelabyrinthopeptin/labyrinthopeptin derivative (ii) is from 1:10 to 10:1,preferably from 1:5 to 5:1, even more preferably from 2:1 to 1:2, andmost preferably 1:1. Or, in other words, the ratio of the concentrationsof the labyrinthopeptin/labyrinthopeptin derivative (i), and thelabyrinthopeptin/labyrinthopeptin derivative (ii) is from 1:10 to 10:1,preferably from 1:5 to 5:1, even more preferably from 2:1 to 1:2, andmost preferably 1:1, wherein the concentration is determined, e.g. inμM.

Assays for testing the anti-viral activity of compounds such aslabyrinthopeptins are commonly known in the art. For example, to testfor the anti-viral activity of the combination of the invention, thecombination may be added to cells (e.g. Huh-7.5 cells). Then, the cellsmay be infected with the virus to be tested (e.g. RSV, KSHV, CMV, DENV,CHIKV, TBEV, VSV, ZIKV and/or HCV, preferably DENV, TBEV and/or ZIKV).The amount of virus-positive cells may be evaluated byimmunocytochemistry. For example, a primary antibody directed againstthe virus and a secondary antibody that has a conjugated fluorophore maybe applied. The number of total cells may be determined by countingDAPI-stained nuclei. Thus, the percentage of virus-positive cells may becalculated. The obtained result is preferably compared to non-infectedcells.

Another aspect of the invention relates to a pharmaceutical compositioncomprising the combination of the present invention, wherein thepharmaceutical composition further comprises a pharmaceuticallyacceptable carrier and/or diluent. The combination of the invention orthe pharmaceutical composition comprising said combination may be usedfor treating and/or preventing a viral infection. Said viral infectionmay be an infection with any one of the viruses selected from RSV, KSHV,CMV, DENV, CHIKV, TBEV, VSV, ZIKV and HCV (e.g. selected from RSV, KSHV,CMV, DENV, CHIKV, TBEV, VSV and ZIKV), preferably selected from DENV,TBEV and ZIKV. Thus, one aspect of the present invention relates to amethod of treating and/or preventing an infection with any one of theviruses selected from RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV andHCV, (e. g. selected from RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV andZIKV; preferably selected from DENV, TBEV and ZIKV), wherein the methodcomprises administering an effective dose of the combination of theinvention, or the pharmaceutical composition comprising said combinationto a subject in need of such a treatment. Preferably, the combination ofthe invention, the pharmaceutical composition comprising saidcombination, or the method of the present invention is used for treatingan existing infectious disease (i.e. an existing viral infection).

One aspect of the invention relates to the herein providedlabyrinthopeptin, labyrinthopeptin derivative, combination,pharmaceutical compositions, or methods, wherein the labyrinthopeptin,the combination or the pharmaceutical composition is co-administeredwith at least one other active agent. Said active agent may be a CMVinhibitor, a KSHV inhibitor, a RSV inhibitor, a DENV inhibitor, a CHIKVinhibitor, a TBEV inhibitor, a VSV inhibitor, a ZIKV inhibitor and/or aHCV inhibitor.

Suitable CMV inhibitors and KSHV inhibitors are known in the art anddescribed, e.g. in Coen, 2014, Viruses 6(11): 4731-59. For example,suitable CMV and KSHV inhibitors include viral DNA polymerase inhibitorssuch as aciclovir, penciclovir, Zidovudine, brivudin, cidofovir HDVD(L-dioxolane uracil analog), Idoxuridin, Famciclovir, Sorivudin,Valaciclovir, Cidofovir, Brincidofovir, Ganciclovir, Valganciclovir,Foscarnet, Maribavir, CMVIG, Letermovir, Leflunomide (antimetabolite,used as a disease-modifying agent in rheumatoid arthritis, has also beensuccessfully used off-label in both CMV disease treatment andprophylaxis) and Fomivirsen.

RSV inhibitors that are useful in the context of the present inventioninclude monoclonal antibodies such as Palivizumab (Motavizumab). Thisantibody represents the only specific therapeutic option currentlyavailable for RSV (Roymans, 2010 Future Med Chem 2(10): 1523-7.). OtherRSV inhibitors that can be used in accordance with the present inventionare nucleoprotein (N-Protein) inhibitors such as RSV604 (Challa, 2015,Antimicrob Agents Chemother 59(2): 1080-7); and RNA interferencemolecules such as ALN-RSV01 (i.e. a small interfering RNA targeting theN-protein of RSV). Such a small interfering RNA is a treatment optionfor the at-risk adult population (DeVincenzo, 2010; Roymans, 2010,Future Med Chem 2(10): 1523-7.). Other RSV inhibitors that may beapplied in context of the invention are nucleoside inhibitors such asALS-8176 (Challa, 2015, Antimicrob Agents Chemother 59(2): 1080-7); orviral fusion inhibitors such as GS-5806 (Gilead®), (DeVincenzo, 2014,Proc Natl Acad Sci USA 107(19): 8800-5.).

DENV inhibitors that may be used in context of the invention includevaccines such as CYD-TDV (recombinant, live, attenuated, tetravalentdengue vaccine). CYD-TDV is currently in clinical trials (Hadinegoro,2015, N Engl J Med 373(13): 1195-206.). Herein “DENV inhibitors” mayfurther include nucleoside analogs (Lim, 2013, Antiviral Res 100(2):500-19.) such as NITD-008 or Balapiravir.

One promising inhibitor of TBEV that may be used in context of thepresent invention is 7-deaza-2-C-methyladenosine (7-deaza-2-CMA).

In another example, the herein provided labyrinthopeptins, combinationor pharmaceutical composition is co-administered with a HCV inhibitor,e.g. with one or a combination of direct acting antiviral(s) targetingeither the HCV NS3/4A protease (telaprevir, boceprevir, simeprevir,paritaprevir, asunaprevir, vaniprevir, vedroprevir, sovaprevir,grazoprevir or ACH-2684), the NSSA phosphoprotein (daclatasvir,ledipasvir, ombitasvir, elbasvir, GS-5816 or ACH-3102) or theRNA-dependent RNA polymerase NSSB (sofosbuvir, MK-3682, ACH-3422,AL-335, dasabuvir, beclabuvir, or GS-9669). Moreover, aco-administration with host targeting antiviral drugs in the context ofHCV infection is conceivable. These include miR-122 targetingtherapeutics like for instance miravirsen or cyclophilin antagonistslike alisporivir, NIM 811, or SCY-635.

The herein provided labyrinthopeptin, labyrinthopeptin derivative,combination, or pharmaceutical composition may be administered bysuitable routes. One aspect of the present invention relates to theherein provided labyrinthopeptin, labyrinthopeptin derivative,combination, pharmaceutical compositions, or methods, wherein thepeptide, the combination or the pharmaceutical composition is to beadministered orally, intravenously, subcutaneously or intramuscularly.Preferably, the administration is intravenously, subcutaneously orintramuscularly. For example, the administration may be intravenously.However, subcutaneous or intramuscular administration has the advantagethat these modes of administration are more practical than intravenousadministration. If the administration is orally, it is envisaged thatthe formulation enables oral bioavailability.

The appended Examples demonstrate that the herein providedlabyrinthopeptin, labyrinthopeptin derivative or combination has highanti-viral activity. Thus, one aspect of the present invention relatesto the labyrinthopeptin of the invention, the labyrinthopeptinderivative of the invention, the combination of the invention, thepharmaceutical compositions of the invention, or the methods of theinvention, wherein the IC50 value of the anti-viral activity of theherein provided labyrinthopeptin, labyrinthopeptin derivative,combination, or pharmaceutical composition is at least 50 μM, preferablyat least 26 μM. Preferably, the labyrinthopeptin of the invention isLabyA1 and the IC50 value is at least 25 μM, more preferably at least 4μM. With respect to the combination of the present invention the IC50value is preferably at least 9 μM, more preferably at least 1.5 μM. Withrespect of the labyrinthopeptin derivative of the present invention thetreated viral infection is preferably an infection with DENV and theIC50 value is preferably at least 7.5 μM. More preferably, thelabyrinthopeptin derivative of the present invention is a derivative ofLabyA1, the treated viral infection is an infection with DENV and theIC50 value is at least 2 μM.

Another aspect of the invention relates to the labyrinthopeptin of theinvention, the labyrinthopeptin derivative of the invention, thecombination of the invention, the pharmaceutical compositions of theinvention, or the methods of the invention, wherein the viral infectionto be treated is an infection with CMV, ZIKV or HCV and the IC50 valueof the anti-viral activity of the herein provided labyrinthopeptin,labyrinthopeptin derivative, combination, or pharmaceutical compositionis at least 5.5 μM. Preferably, the labyrinthopeptin of the presentinvention is LabyA1, the viral infection to be treated and/or preventedis an infection with CMV, or HCV and the IC50 value is at least 1.5 μM.

A further aspect of the invention relates to the labyrinthopeptin of theinvention, the labyrinthopeptin derivative of the invention, thecombination of the invention, the pharmaceutical compositions of theinvention, or the methods of the invention, wherein the viral infectionto be treated is an infection with DENV and the IC50 value of theanti-viral activity of the herein provided labyrinthopeptin,labyrinthopeptin derivative, combination, or pharmaceutical compositionis at least 8 μM. Preferably, the labyrinthopeptin of the presentinvention is LabyA1, the viral infection to be treated and/or preventedis an infection with DENV and the IC50 value is at least 2 μM.

A further aspect of the invention relates to the labyrinthopeptin of theinvention, the labyrinthopeptin derivative of the invention, thecombination of the invention, the pharmaceutical compositions of theinvention, or the methods of the invention, wherein the labyrinthopeptinof the present invention is LabyA1, the viral infection to be treatedand/or prevented is an infection with CHIKV and the IC50 value is atleast 2 μM.

Table 3 shows the IC50 values of the anti-viral activities of LabyA1,LabyA2, the combination of LabyA1 and LabyA2 (LabyA1/A2), the LabyA1derivative “LabyA1-hexyn” (herein also called “LabyA1-Hexyn”), theLabyA2 derivative “LabyA2-hexyn” (herein also called “LabyA2-Hexyn”), aswell as the combination of LabyA1-hexyn and LabyA2-hexyn(LabyA1/A2-hexyn).

TABLE 3 IC50 values (in μM and μg/ml) of the anti-viral activity oflabyrinthopeptins, combinations of labyrinthopeptins andlabyrinthopeptin derivatives. LabyA1 LabyA2 LabyA1/A2 LabyA1-hexynLabyA2-hexyn LabyA1/A2 - hexyn μM μg/ml μM μg/ml μM μg/ml μM μg/ml μMμg/ml μM μg/ml DENV 1.78 3.7 8.00 15.4 1.30 2.6 1.70 3.7 7.03 14.2 0.962.0 RSV 0.39¹ 0.8¹ 4.97¹ 9.56¹ — — — — — — — — KSHV 2 4.2 15 28.9 — — —— — — — — TBEV 24.10 50 >25.99 >50 8.34 16.67 — — — — — — CMV 1.3 2.75.4 μM 10.4 — — — — — — — — CHIKV 0.5-1.7 1.0-3.5 — — — — — — — — — —VSV 1.1-3.7 2.3-7.7 — — — — — — — — — — ZIKV 2.22 4.6 2.81 5.4 1.75 3.5— — — — — — HCV 1.05 2.18 1.728 3.32 — — — — — — — — LabyA1 = LabyA2 =LabyA1-hexyn = LabyA2-hexyn = 2075.33 g/mol 1924.16 g/mol 2170.45 g/mol2019.28 g/mol ¹These values are measured by intracellular RSV-P staining(see FIG. 16C).

For RSV the appended examples also show somehow higher IC50 values (seeFIGS. 16A and 16B). However, these higher values have been obtained byusing an indirect high throughput screening assay (FIG. 15). In thisindirect high throughput screening assay the antiviral activity ofcompounds is roughly estimated based on the ability of a compound torescue cell survival upon challenge with RSV which is a lytic virus.Since the host cells used in this assay constitutively express aluciferase reporter gene, changes in cell survival can be quantified byluciferase assays. However, due to the indirect nature of this assay,the precision of IC50 values is limited. In other experiments summarizedin FIG. 16C the IC50 of labyrinthopeptins against RSV were preciselydetermined by using a direct, quantitative assay that measures RSVdependent protein expression in the infected cells. Specifically, inthis assay cells are inoculated with RSV (i.e. hRSV) in the presence orabsence of the compound to be tested (e.g. labyrinthopeptins).Subsequently, infection efficiency is determined by using anintracellular FACS staining based on hRSV P protein detection, e.g. byusing a mouse monoclonal antibody. Using this approach it is possible todirectly determine the number of RSV infected cells; and thus preciselyquantify the IC50.

As demonstrated in the appended Examples, labyrinthopeptins(particularly LabyA1) have a high anti-viral activity against CMV. Thus,in a preferred aspect of the herein provided labyrinthopeptin,labyrinthopeptin derivative, combination, pharmaceutical compositions,or methods, the treated viral infection is an infection with CMV (i.e.HCMV).

As mentioned above, the appended Examples show that a combination ofLabA1 and LabyA2 results in a synergistic effect in the treatment ofviruses. For example, a synergistic activity of LabyA1 and LabyA2 in theanti-viral activity against DENV, TBEV or ZIKV has been shown. Thus,particularly in the context of the herein provided combination, theviral infection is preferably an infection with DENV, TBEV and/or ZIKV.

The terms “labyrinthopeptin(s) of the (present) invention”,“labyrinthopeptin(s) provided herein”, and “herein providedlabyrinthopeptin(s)” are used interchangeably herein. These terms referto peptides (i.e. compounds) as defined in SEQ ID NO: 2 that exhibitanti-viral activity, particularly against RSV, KSHV, CMV, DENV, CHIKV,TBEV, VSV, ZIKV and HCV, which may be measured using methods known inthe art. For example, to test for the anti-viral activity of thelabyrinthopeptin of the invention, the labyrinthopeptin of the inventionmay be added to cells (e.g. Huh-7.5 cells). Then, the cells may beinfected with the virus to be tested (e.g. RSV, KSHV, CMV, DENV, CHIKV,TBEV, VSV, ZIKV and/or HCV). The amount of virus-positive cells may beevaluated by immunocytochemistry. For example, a primary antibodydirected against the virus and a secondary antibody that has aconjugated fluorophore may be applied. The number of total cells may bedetermined by counting DAPI-stained nuclei. Thus, the percentage ofvirus-positive cells may be calculated. The obtained result ispreferably compared to non-infected cells.

Particularly, the terms “labyrinthopeptin(s) of the (present)invention”, “labyrinthopeptin(s) provided herein”, and “herein providedlabyrinthopeptin(s)” refer to a peptide (i.e. compound) that comprisesor consists of the amino acid sequence (from N- to C-terminus)

wherein

-   Lab is labionin-   X₁ is an amino acid selected from Asn, Asp, and Glu;-   X₂ is an amino acid selected form Ala, Trp, and Ser;-   X₃ is an amino acid selected from Val, Leu, and Ile;-   X₄ is an amino acid selected from Trp and Tyr;-   X₅ is an amino acid selected from Glu and Asp;-   X₆ is an amino acid selected from Thr and Ser;-   X₇ is an amino acid selected from Gly and Pro; and-   X₈ consists of a sequence of 3 to 5 amino acids.

The amino acid sequence of SEQ ID NO: 2 starts with the N-terminus andends with the C-terminus, i.e. the sequence of SEQ ID NO: 2 is displayedfrom N- to C-terminus.

Preferred amino acids for the positions X₁, X₂, X₃, X₄, X₅, X₇ and X₈are described herein above. In SEQ ID NO: 2 “-” is a chemical bond. If“-” is placed between “X” and “X” (e.g. X₁-X₂, X₃-X₄, X₄-X₅, or X₆-X₇)or between “X” and “Lab” (e.g. “Lab-X₁”, X₂-Lab”, “Lab-X₃”, “X₅-Lab”,“Lab-Cys”, “Lab-X₆”, “X₇-Lab”, “Lab-X₈”), than “-” is preferably apeptide bond/linkage. “—S—S—” is a disulfide bridge (also calledSS-bond). “—S—” is a thioether bridge between the β-C-atoms of the twoalanine-residues that represent the lanthionine part of Lab.

The labionins at positions 1 and 4 of SEQ ID NO: 2 (counted from theN-terminus) and the labionins at positions 10 and 13 of SEQ ID NO: 2(counted from the N-terminus) are linked via a methylene bridge (i.e.—CH₂—). In particular, a methylene group links the αC atoms of thelabionins at positions 1 and 4 of SEQ ID NO: 2. Another methylene grouplinks the αC atoms of the labionins at positions 10 and 13 of SEQ ID NO:2.

As mentioned above, a preferred aspect of the present invention relatesto a combination or LabyA1 and LabyA2 (i.e. the combination of thepresent invention). With respect to the labyrinthopeptin of the presentinvention, LabyA1 and LabyA2 are preferred; LabyA1 is more preferred.The amino acid sequence (including the internal bridges) of LabyA1 isshown in the following SEQ ID NO: 3:

wherein Dhb is dehydrobutyrine (also called didehydrobutyrine), and Labis labionin. The structure of Dhb is shown in FIG. 2.

The amino acid sequence (including the internal bridges) of LabyA2 isshown in the following SEQ ID NO: 4:

wherein Lab is labionin.

The labyrinthopeptins of the present invention also include peptidesthat have at least 80%, preferably at least 85%, more preferably atleast 90%, and even more preferably at least 95% sequence identity tothe amino acid sequence as shown in SEQ ID NO: 3, wherein the peptidehas at least 50%, preferably at least 90% of the anti-viral activity ofLabyA1, particularly against RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV,ZIKV and/or HCV. The labyrinthopeptins of the present invention furtherinclude peptides that have at least 80%, preferably at least 85%, morepreferably at least 90%, and even more preferably at least 94% sequenceidentity to the amino acid sequence as shown in SEQ ID NO: 4, whereinthe peptide has at least 50%, preferably at least 90% of the anti-viralactivity of LabyA2, preferably against RSV, KSHV, CMV, DENV, TBEV, ZIKVand/or HCV.

The labyrinthopeptins of the present invention also include peptideanalogs and peptidomimetics (or peptide mimetics), that exhibitanti-viral activity, particularly against RSV, KSHV, CMV, DENV, CHIKV,TBEV, VSV, ZIKV and/or HCV.

The labyrinthopeptins of the present invention include a peptide of SEQID NO: 2, 3, or 4 in any stereochemical form, or a mixture of anystereochemical forms in any ratio. Unless otherwise indicated, thechiral centers in the peptide of SEQ ID NO: 2, 3, or 4 can be present inthe R configuration or in the S configuration. The invention relates toboth optically pure compounds and to stereoisomeric mixtures, such asenantiomeric mixtures and diastereomeric mixtures. Preferably, thelabyrinthopeptin of the present invention has the stereochemistry ofnatural LabyA1 or LabyA2 as shown in FIG. 3.

The labyrinthopeptins of the present invention are described herein(e.g. by SEQ ID NO: 2). However, the labyrinthopeptins of the presentinvention also comprise the modified labyrinthopeptins as disclosed inKrawczyk, Chemistry & Biology, 2013, 20(1), 111-122; and WO 2013/092672,provided that these modified labyrinthopeptins have anti-viral activity,particularly against RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/orHCV.

In addition, the terms “labyrinthopeptin(s) of the (present) invention”,“labyrinthopeptin(s) provided herein”, and “herein providedlabyrinthopeptin(s)”, also relate to a pharmaceutical acceptable salt ofa peptide as defined in SEQ ID NO: 2, 3, or 4. Thus, also pharmaceuticalacceptable salts are included by the term “labyrinthopeptin of thepresent invention”.

The terms “labyrinthopeptin derivative(s) of the (present) invention”,“labyrinthopeptin derivative(s) provided herein”, and “herein providedlabyrinthopeptin derivative(s)” are used interchangeably herein. Theseterms refer to peptides (i.e. compounds) as defined in SEQ ID NO: 1,that exhibit anti-viral activity, particularly against RSV, KSHV, CMV,DENV, CHIKV, TBEV, VSV, ZIKV and/or HCV, preferably against DENV, whichmay be measured using methods known in the art. For example, to test forthe anti-viral activity of labyrinthopeptin derivatives of theinvention, the labyrinthopeptin derivative of the invention may be addedto cells (e.g. Huh-7.5 cells). Then, the cells may be infected with thevirus to be tested (e.g. RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKVand/or HCV, preferably DENV). The amount of virus-positive cells may beevaluated by immunocytochemistry. For example, a primary antibodydirected against the virus and a secondary antibody that has aconjugated fluorophore may be applied. The number of total cells may bedetermined by counting DAPI-stained nuclei. Thus, the percentage ofvirus-positive cells may be calculated. The obtained result ispreferably compared to non-infected cells.

Particularly, the terms “labyrinthopeptin derivative(s) of the (present)invention”, “labyrinthopeptin derivative(s) provided herein”, and“herein provided labyrinthopeptin derivative(s)” refer to a peptide(i.e. compound) that comprises or consists of the amino acid sequence(from N- to C-terminus)

wherein

-   Lab is labionin-   X₁ is an amino acid selected from Asn, Asp, and Glu;-   X₂ is an amino acid selected form Ala, Trp, and Ser;-   X₃ is an amino acid selected from Val, Leu, and Ile;-   X₄ is an amino acid selected from Trp and Tyr;-   X₅ is an amino acid selected from Glu and Asp;-   X₆ is an amino acid selected from Thr and Ser;-   X₇ is an amino acid selected from Gly and Pro;-   X₈ consists of a sequence of 3 to 5 amino acids;-   R₁ is selected from H, a (C₂-C₁₂)alkynyl, a C(O)—(C₂-C₁₂)alkynyl, a    C(O)—O—(C₂-C₁₂)alkynyl, and a C(O)NH—(C₂-C₁₂)alkynyl; wherein R₁    carries the alkynyl group at the terminal position, and-   R₂ is selected from H, a [C(O)]—NH—(C₂-C₁₂)alkynyl or a    [C(O)]—O—(C₂-C₁₂)alkynyl; wherein the moiety [C(O)] is the carbonyl    group of the terminal amino acid; wherein R₂ carries the alkynyl    group at the terminal position;    wherein if R₁ is H, then R₂ is not H.

The amino acid sequence of SEQ ID NO: 1 starts with the N-terminus andends with the C-terminus, i.e. the sequence of SEQ ID NO: 1 is displayedfrom N- to C-terminus.

Preferred amino acids for the positions X₁, X₂, X₃, X₄, X₅, X₇ and X₈are described herein above. In SEQ ID NO: 1 “-” is a chemical bond. If“-” is placed between “X” and “X” (e.g. X₁-X₂, X₃-X₄, X₄-X₅, or X₆-X₇)or between “X” and “Lab” (e.g. “Lab-X₁”, X₂—Lab”, “Lab-X₃”, “X₅-Lab”,“Lab-Cys”, “Lab-X₆”, “X₇-Lab”, “Lab-X₈”), than “-” is preferably apeptide bond/linkage. “—S—S—” is a disulfide bridge (also calledSS-bond). “—S—” is a thioether bridge between the β-C-atoms of the twoalanine-residues that represent the lanthionine part of Lab.

The labionins at positions 1 and 4 of SEQ ID NO: 1 (counted from theN-terminus) and the labionins at positions 10 and 13 of SEQ ID NO: 1(counted from the N-terminus) are linked via a methylene bridge (i.e.—CH₂—). In particular, a methylene group links the αC atoms of thelabionins at positions 1 and 4. Another methylene group links the αCatoms of the labionins at positions 10 and 13 of SEQ ID NO: 1.

Preferred labyrinthopeptins within the labyrinthopeptin derivative ofthe present invention are LabyA1 and LabyA2, LabyA1 is most preferred.The amino acid sequence (including the internal bridges) of LabyA1 isshown in SEQ ID NO: 3 above.

Thus, in a preferred aspect, the labyrinthopeptin derivative of thepresent invention is a derivative of LabyA1 as shown in the followingFormula (I):

In an even more preferred aspect, the labyrinthopeptin derivative of thepresent invention is a derivative of LabyA1 as shown in the followingFormula (II):

In an even more preferred aspect, the labyrinthopeptin derivative of thepresent invention is “LabyA1-Hexyn” as shown in FIG. 4.

In another preferred aspect, the labyrinthopeptin derivative of thepresent invention is a derivative of LabyA2 as shown in the followingFormula (III):

In an even more preferred aspect, the labyrinthopeptin derivative of thepresent invention is a derivative of LabyA2 as shown in the followingFormula (IV):

In an even more preferred aspect, the labyrinthopeptin derivative of thepresent invention is “LabyA2-Hexyn” as shown in FIG. 4.

The explanations of R₁ and R₂ that have been given with respect to SEQID NO: 1 apply, mutatis mutandis, also for Formulae I-IV.

The labyrinthopeptin derivative of the present invention also includelabyrinthopeptin derivatives comprising (in addition to R₁ and/or R₂)peptides that have at least 80%, preferably at least 85%, morepreferably at least 90%, and even more preferably at least 95% sequenceidentity to the amino acid sequence as shown in SEQ ID NO: 3, whereinthe peptide has at least 50%, preferably at least 90% of the anti-viralactivity of LabyA1, particularly against RSV, KSHV, CMV, DENV, CHIKV,TBEV, VSV, ZIKV and/or HCV, more preferably against DENV. Thelabyrinthopeptin derivative of the present invention further includelabyrinthopeptin derivatives comprising (in addition to R₁ and/or R₂)peptides that have at least 80%, preferably at least 85%, morepreferably at least 90%, and even more preferably at least 94% sequenceidentity to the amino acid sequence as shown in SEQ ID NO: 4, whereinthe peptide has at least 50%, preferably at least 90% of the anti-viralactivity of LabyA2, preferably against RSV, KSHV, CMV, DENV, TBEV, ZIKVand/or HCV, more preferably against DENV.

The labyrinthopeptin derivatives of the present invention also includepeptide analogs and peptidomimetics (or peptide mimetics), that exhibitanti-viral activity, particularly against RSV, KSHV, CMV, DENV, CHIKV,TBEV, VSV, ZIKV and/or HCV.

The labyrinthopeptin derivative of the present invention includes alabyrinthopeptin derivative comprising a peptide of SEQ ID NO: 1 in anystereochemical form, or a mixture of any stereochemical forms in anyratio. Unless otherwise indicated, the chiral centers in the peptide ofSEQ ID NO: 1 can be present in the R configuration or in the Sconfiguration. The invention relates to both optically pure compoundsand to stereoisomeric mixtures, such as enantiomeric mixtures anddiastereomeric mixtures. Preferably, the labyrinthopeptin derivative ofthe present invention comprises (in addition to R₁ and/or R₂) a peptidehaving the stereochemistry of natural LabyA1 or LabA2 as shown in FIG.3.

The labyrinthopeptin derivatives of the present invention are describedherein (e.g. by SEQ ID NO: 1). However, the labyrinthopeptin derivativesof the present invention may also comprises (in addition to R₁ and/orR₂) the modified labyrinthopeptins as disclosed in Krawczyk, Chemistry &Biology, 2013, 20(1), 111-122; and WO 2013/092672, provided that thesemodified labyrinthopeptins have anti-viral activity, particularlyagainst RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/or HCV.

In addition, the terms “labyrinthopeptin derivative(s) of the (present)invention”, “labyrinthopeptin derivative(s) provided herein”, and“herein provided labyrinthopeptin derivative(s)” also relate to apharmaceutical acceptable salt of a peptide as defined in SEQ ID NO: 1.Thus, also pharmaceutical acceptable salts are included by the term“labyrinthopeptin derivative of the present invention”.

“Peptide analogs” (also called “peptidomimetics” or “peptide mimetics”)are commonly used in the pharmaceutical art as non-peptide drugs withproperties analogous to those of a “template” peptide. The peptideanalogs/peptidomimetics replicate the backbone geometry andphysico-chemical properties of biologically active peptides.Peptidomimetics that are structurally related to biologically activepeptides may be used to produce an equivalent or enhanced biologicalactivity (e.g., enhanced therapeutic and/or prophylactic effect).Generally, peptidomimetics are structurally similar to the templatepeptide, i.e. a peptide that has biological or pharmacological activityand that comprises naturally-occurring amino acids, but have one or morepeptide linkages replaced by linkages such as —CH₂NH—, —CH₂S—,—CH₂—CH₂—, —CH═CH— (cis and trans), —CH₂SO—, —CH(OH)CH₂—, —COCH₂— etc.Such peptidomimetics can be prepared by methods well known in the art(see, e.g., Spatola, Peptide Backbone Modifications, Vega Data, 1:267,1983; Spatola, Life Sei. 38:1243-1249, 1986; Hudson, Int. J. Pept. Res.14:177-185, 1979; and Weinstein, 1983, Chemistry and Biochemistry, ofAmino Acids, Peptides and Proteins, Weinstein eds, Marcel Dekker,New-York). Such peptidomimetics may have certain advantages includingmore economical production, greater chemical stability, enhancedpharmacological properties (e.g., half-life, absorption, potency,efficiency, etc.), reduced antigenicity and others.

The term “amino acid” or “residue” as used herein includes both, L- andD-isomers of the naturally occurring amino acids as well as of otheramino acids (e.g., non-naturally-occurring amino acids, amino acidswhich are not encoded by nucleic acid sequences, synthetic amino acids,etc.). Examples of naturally-occurring amino acids are alanine (Ala; A),arginine (Arg; R), asparagine (Asn; N), aspartic acid (Asp; D), cysteine(Cys; C), glutamine (Gln; Q), glutamic acid (Glu; E), glycine (Gly; G),histidine (His; H), isoleucine (Ile; I), leucine (Leu; L), lysine (Lys;K), methionine (Met; M), phenylalanine (Phe; F), proline (Pro; P),serine (Ser; S), threonine (Thr; T), tryptophane (Trp; W), tyrosine(Tyr; Y), valine (Val; V). Post-translationally modifiednaturally-occurring amino acids are dehydrobutyrine (Dhb) and labionin(Lab). The labyrinthopeptin of the present invention or thelabyrinthopeptin that is comprised in the labyrinthopeptin derivative ofthe present invention may consist of naturally-occurring amino acids.The labyrinthopeptin of the present invention or the labyrinthopeptinthat is comprised in the labyrinthopeptin derivative of the presentinvention may consist of L amino acids. Amino acids are abbreviatedherein by the one-letter code or the three-letter code as commonly usedin the art and as also set forth hereinabove.

In addition to labionin and dehydrobutyrine, naturally-occurringnon-genetically encoded amino acids and synthetic amino acids include,beta-alanine, 3-aminopropionic acid, 2,3-diamino propionic acid,alpha-aminoisobutyric acid (Aib), 4-amino-butyric acid, N-methylglycine(sarcosine), hydroxyproline, ornithine (e.g., L-ornithine), citrulline,tbutylalanine, f-butylglycine, N-methylisoleucine, phenylglycine,cyclohexylalanine, norleucine (Nie), norvaline, 2-napthylalanine,pyridylalanine, 3-benzothienyl alanine, 4-chlorophenylalanine,2-fluorophenylalanine, 3-fluorophenylalanine, 4-fluorophenylalanine,penicillamine, 1,2,3,4-tetrahydro-isoquinoline-3-carboxylix acid,beta-2-thienylalanine, methionine sulfoxide, L-homoarginine (Harg),N-acetyl lysine, 2-amino butyric acid, 2-amino butyric acid,2,4,-diaminobutyric acid (D- or L-), p-aminophenylalanine,N-methylvaline, homocysteine, homoserine, cysteic acid, epsilon-aminohexanoic acid, delta-amino valeric acid, and 2,3-diaminobutyric acid (D-or L-), etc. Unnatural amino acids include, e.g., β-amino acids (β³ andβ²), homo-amino acids, 3-substituted alanine derivatives,ring-substituted phenylalanine and tyrosine derivatives, linear coreamino acids, and N-methyl amino acids. These amino acids are well knownin the art of biochemistry/peptide chemistry.

The term “amino acid” also refers to synthetic amino acids providingsimilar side chain functionality. For example, aromatic amino acids maybe replaced with D- or L-naphthylalanine, D- or L-phenylglycine, D- orL-2-thienylalanine, D- or L-1-, 2-, 3-, or 4-pyrenylalanine, D- orL-3-thienylalanine, D- or L-(2-pyridinyl)-alanine, D- orL-(3-pyridinyl)-alanine, D- or L-(2-pyrazinyl)-alanine, D- orL-(4-isopropyl)-phenyl glycine, D-(trifluoromethyl)-phenylglycine,D-(trifluoromethyl)-phenylalanine, D-p-fluorophenylalanine, D- orL-pbiphenylalanine D- or L-p-methoxybiphenylalanine, D- orL-2-indole(alkyl)alanines, and D- or Lalkylalanines wherein the alkylgroup is selected from the group consisting of substituted orunsubstituted methyl, ethyl, propyl, hexyl, butyl, pentyl, isopropyl,iso-butyl, and iso-pentyl. Non-carboxylate amino acids can be made topossess a negative charge, as provided by phosphono- or sulfated aminoacids, which are to be considered as non-limiting examples.

The term “amino acid” also includes unnatural alkylated amino acids,made by combining an alkyl group with any natural amino acid. Basicnatural amino acids such as lysine and arginine may be substituted withalkyl groups at the amine (NH₂) functionality. Yet other substitutionsinclude nitrile derivatives (e.g., containing a CN-moiety in place ofthe CONH₂ functionality) of asparagine or glutamine, and sulfoxidederivative of methionine.

In the labyrinthopeptin of the present invention or the labyrinthopeptinderivative of the present invention all amino acids may be L-aminoacids. Alternatively, all amino acids may be D-amino acids. In anotheralternative, the peptide/peptide compound may comprise a mixture of L-and D-amino acids. For example, the therein provided labyrinthopeptin orlabyrinthopeptin derivative may comprise at least one D-amino acid,which is located in the N-terminal and/or C-terminal portion (e.g.,within the last 2 or 3 N- and/or C-terminal residues). The presence ofone or more D-amino acids typically results in peptides having increasedstability (e.g., in vivo) due to decreased susceptibility toprotease/peptidase cleavage, but retain biological activity.

The labyrinthopeptin and/or labyrinthopeptin derivative of the presentinvention may comprise, further to the compound as defined in SEQ IDNOs: 1 or 2, respectively, one or more amino acids covalently linked tothe amino and/or carboxy-termini. Thus, the labyrinthopeptin and/orlabyrinthopeptin derivative of the present invention may be a chimericor fusion protein comprising SEQ ID NO: 1 or 2, respectively, linked atits N (i.e. amino)- or C (i.e. carboxy)-terminal end, or both, toanother amino acid sequence. Thus, one aspect of the present inventionrelates to the herein provided labyrinthopeptin (i.e. SEQ ID NO: 2)comprising at its N- and/or C-terminus an amino acid sequence of 0-10amino acids, preferably of 0-5 amino acids, more preferably of 0-3 aminoacids. Similarly, the herein provided labyrinthopeptin derivative may bethe herein provided labyrinthopeptin derivative (i.e. SEQ ID NO: 1)comprising at its C-terminus or at its N-terminus an amino acid sequenceof 0-10 amino acids, preferably of 0-5 amino acids, more preferably of0-3 amino acids. For example, the labyrinthopeptin/labyrinthopeptinderivative of the present invention may comprise a peptide moiety and/oran antibody for targeting the labyrinthopeptin/labyrinthopeptinderivative to a particular cell, tissue and/or organ. For example, thepeptide moiety and/or antibody may direct thelabyrinthopeptin/labyrinthopeptin derivative to the liver (e.g. tohepatocytes). For the treatment of a DENV infection, the peptide moietyand/or antibody may direct the labyrinthopeptin/labyrinthopeptinderivative to cells of the immune system (e.g. to T-cells or Langerhansdendritic cells). For the treatment of an infection with Herpesviridaepeptide moiety and/or antibody may direct thelabyrinthopeptin/labyrinthopeptin derivative to nerve cells (e.g. tooligodendrocytes or neurons). For the treatment of an infection with RSVthe peptide moiety and/or antibody may direct thelabyrinthopeptin/labyrinthopeptin derivative to the lung (e.g. to thealveolae). For the treatment of an infection with CHIKV the peptidemoiety and/or antibody may direct the labyrinthopeptin derivative tomuscle, joint or nerve tissue. For the treatment of an infection withTBEV the peptide moiety and/or antibody may direct the labyrinthopeptinderivative to cells of the central nervous tissue (brain, spinal cord).For the treatment of an infection with ZIKV the peptide moiety and/orantibody may direct the labyrinthopeptin derivative to subcutaneoustissue, the central nervous system, the skeletal muscles or themyocardium. For the treatment of an infection with HCV the peptidemoiety and/or antibody may direct the labyrinthopeptin/labyrinthopeptinderivative to the liver (e.g. to hepatocytes).

The labyrinthopeptin or labyrinthopeptin derivative of the invention maycomprise two or more compounds of SEQ ID NO: 1 or SEQ ID NO: 2,respectively, covalently linked to one another either directly orindirectly (through a spacer or linker). For example, thelabyrinthopeptin of the invention may be a fusion protein comprising twoor more linked LabyA1-subunits, two or more linked LabyA2-subunits, orone or more LabyA1-subunits linked to one or more LabyA2-subunits.

Also encompassed in the present invention is a labyrinthopeptin asprovided herein, wherein the N- and/or C-terminal amino acids aremodified. Similarly, in the labyrinthopeptin derivative provided hereinthe C-terminal or the N-terminal amino acid may be modified. Possiblemedications include amidation, acetylation, acylation, covalentattachment of fatty acids (e.g., C6-C18), attachment of proteins such asalbumin (see, e.g., U.S. Pat. No. 7,268,113); glycosylation,biotinylation or PEGylation acetylation, acylation, addition ofacetomidomethyl (Acm) group, ADP-ribosylation, alkylation, amidation,carbamoylation, carboxyethylation, esterification, covalent attachmentof flavin, covalent attachment of a heme moiety, covalent attachment ofa nucleotide or nucleotide derivative, covalent attachment of a drug,covalent attachment of a marker (e.g., a fluorescent or radioactivemarker), covalent attachment of a lipid or lipid derivative, covalentattachment of phosphatidylinositol, demethylation, formation of covalentcrosslinks, formation of cystine, formation of pyroglutamate,formylation, gamma-carboxylation, glycosylation, GPI anchor formation,hydroxylation, iodination, methylation, myristoylation, oxidation,proteolytic processing, phosphorylation, prenylation, racemization,selenoylation, sulfation, and ubiquitination.

As described above, herein the terms “labyrinthopeptin of the (present)invention” and “labyrinthopeptin derivative of the (present) invention”also include a salt of the labyrinthopeptin/labyrinthopeptin derivativeas provided herein, e.g., a pharmaceutically acceptable salt of thecompound as described in SEQ ID NO: 1 or 2. Pharmaceutically acceptablesalts of the labyrinthopeptin/labyrinthopeptin derivative as providedherein are understood as being both their organic salts and theirinorganic salts, as are described in Remington's Pharmaceutical Sciences(17th edition, page 1418 (1985)). Because of their physical and chemicalstability and their solubility, sodium, potassium, calcium and ammoniumsalts are preferred, inter alia, for acid groups; salts of hydrochloricacid, sulfuric acid or phosphoric acid, or of carboxylic acids orsulfonic acids, such as acetic acid, citric acid, benzoic acid, maleicacid, fumaric acid, tartaric acid and p-toluenesulfonic acid, arepreferred, inter alia, for basic groups. As used herein the term“pharmaceutically acceptable salt” refers to salts of thelabyrinthopeptin/labyrinthopeptin derivative of the present inventionthat retain the anti-viral activity of the parent compound (particularlyagainst RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/or HCV,preferably DENV), and which are not biologically or otherwiseundesirable (e.g. not toxic). Such salts can be prepared in situ duringthe final isolation and purification of thelabyrinthopeptin/labyrinthopeptin derivative, or separately prepared byreacting a free base function with a suitable acid.

The labyrinthopeptins of the present invention (e.g. LabyA1 and/orLabyA2) may be produced as follows. The fermentation of biomass from thepublicly available type strain Actinomadura namibiensis (DSM 6313) maybe performed as described before (Meindl, 2010, Angew Chem Int Ed Engl49: 1151-1154). Afterwards, biomass from the fermenter may be suspendedin water (e.g. 2 L), extracted with acetone (e.g. 2×2 L) and methanol(e.g. 1)(24 Then, combined organic layers may be evaporated undervacuum. Obtained crude compound may be suspended in water (e.g. 1 L) andextracted with tert-butylmethylether (e.g. 2×1 L). Afterwards, organiclayer may be discarded and the aqueous layer may be evaporated to obtain(e.g. 20 g of) crude material. The crude compound may be subjected topurification (e.g. in 2 g batches). Purification may be performed on aflash chromatography system (e.g. Reveleris X2 from GRACE) with a C18-WP(40 g, 20μ) column using acetonitrile in water (10-90%) with 0.1% HCOOHas eluents. After the purification, the amount of crude mixture of thelabyrinthopeptins of the invention (e.g. of LabyA1 and/or LabA2) may bereduced to 2 g which may further be purified by reverse-phase HPLC usinga Gemini 5μ C18 column (dimension: 250 mm×20 mm) with acetonitrile inwater (10-90%) with 0.1% HCOOH as eluents. Peaks may be fractionatedbased on the UV detection at 220 nm. Collected desired compounds (i.e.the labyrinthopeptin of the present invention) may be lyophilized. Thisprocedure may yield approximately 40 mg of LabyA1 and approximately 6 mgof LabyA2.

The labyrinthopeptin of the present invention may also be produced asdescribed in WO 2013/092672 A2, wherein recombinant production oflabyrinthopeptidns is disclosed. Thus, the labyrinthopeptin of thepresent invention may be produced by expression in a host cellcomprising a nucleic acid encoding the labyrinthopeptin (recombinantexpression). Alternatively, LabyA1 and/or LabyA2 may be isolated fromActinomadura namibiensis (i.e. wild-type Actinomadura namibiensis) asdescribed in WO 2008/040469 A1, WO 2009/121483 A1 or WO 2009/121483 A1.Therefore, the Actinomadura namibiensis stain DSM 6313 as disclosed inWO 2009/121483 A1 or WO 2009/121483 A1 may be used. The labyrinthopeptinof the present invention may also be isolated and purified as describedin Meindl (2010, Angew Chem Int Ed Engl 49: 1151-1154). In brief, thelabyrinthopeptin of the present invention may be purified by extraction,chromatography and preparative HPLC as a final purification step.

Different labyrinthopeptin species may be separated on the basis oftheir differing polarities, by means of reversed phase chromatography,for example on MCI (adsorber resin, Mitsubishi, Japan) or Amberlite XAD(TOSOHAAS), or on other hydrophobic materials, for example on RP-8 orRP-18 phases. In addition, the separation can be effected by means ofnormal-phase chromatography, for example on silica gel, aluminum oxideand the like.

The labyrinthopeptin/labyrinthopeptin derivative of the presentinvention may also be prepared by chemical synthesis (e.g., solid-phasepeptide synthesis). The quality of the labyrinthopeptin/labyrinthopeptinderivative may be checked by UV and NMR spectroscopy.

The labyrinthopeptin derivatives of the present invention (e.g.LabyA1-Hexyn or LabyA2-Hexyn as shown in FIG. 4) may be produced asfollows. To a solution of 2-chloro-4,6-dimethoxy-1,3,5-triazine (e.g. 1mg, 0.006 mmol) in dimethylformamide (e.g. 1 ml), n-methylmorpholine(e.g. 2 μL, 0.015 mmol) may be added at room temperature. After 1 hstirring at room temperature, the compound to be added (e.g. 5-Hexynoicacid if R₁ should be hex-5ynoyl; e.g. 0.5 μL, 0.004 mmol) may be added.After 30 minutes of stirring, the non-derivatized labyrinthopeptin (e.g.6 mg, 0.003 mmol) may be added to the reaction mixture and allowed tostir for 16 h at room temperature. The reaction mixture may be purifiedby reversed-phase HPLC using a Gemini 5μ C18 column (dimension: 250mm×20 mm) with acetonitrile in water (10-90%) with 0.1% HCOOH aseluents. Peaks may be fractionated based on the UV detection at 220 nm.The collected derivatized labyrinthopeptin may be lyophilized to yield 2mg (31.7%). The product may be characterized by high resolution massspectrometry.

The present invention also provides a nucleic acid encoding thelabyrinthopeptin of the present invention, a cell (e.g., a host cell)comprising the above-mentioned nucleic acid and/or a vector. Thus, theinvention provides a recombinant expression system, vectors and hostcells for the expression/production of the labyrinthopeptin of theinvention, using for example culture media, production, isolation andpurification methods well known in the art. As indicated above, thelabyrinthopeptin of the invention can be purified by techniques ofpeptide purification well known in the art, such as reverse phasechromatography, high performance liquid chromatography (HPLC), ionexchange chromatography, size exclusion chromatography, affinitychromatography, gel electrophoresis, and the like. For affinitychromatography purification, any antibody which specifically binds theherein provided labyrinthopeptin/labyrinthopeptin derivative may forexample be used.

The present invention also provides a pharmaceutical compositioncomprising the above-described labyrinthopeptin and/or labyrinthopeptinderivative and/or combination. Said pharmaceutical composition furthercomprises at least one pharmaceutically acceptable carrier and/ordiluent. As used herein, the term “pharmaceutically acceptable” (alsocalled “biologically acceptable”) refers to materials characterized bythe absence of (or limited) toxic or adverse biological effects in vivo.The term “pharmaceutically acceptable carrier and/or diluent” refers toadditives commonly used in the preparation of pharmaceuticalcompositions and includes, for example, solvents, dispersion media,saline solutions, surfactants, solubilizing agents, lubricants,emulsifiers, coatings, antibacterial and antifungal agents, chelatingagents, pH-modifiers, soothing agents, buffers, reducing agents,antioxidants, isotonic agents, absorption delaying agents or the like(see, e.g., Rowe et al., Handbook of Pharmaceutical Excipients,Pharmaceutical Press; 6th edition, 2009).

As described above, the herein provided pharmaceuticalcompositions/labyrinthopeptins/labyrinthopeptin derivatives/combinationscan be administered parenterally, for example intravenously,intramuscularly or subcutaneously, e.g. in the form of injectionsolutions or infusion solutions, microcapsules, implants or rods. Thepharmaceutical compositions/labyrinthopeptins/labyrinthopeptinderivatives/combinations of the present invention can also beadministered orally, for example in the form of pills, tablets,lacquered tablets, coated tablets, granules, hard and soft gelatincapsules, solutions, syrups, emulsions, suspensions or aerosol mixtures.However, the pharmaceuticalcompositions/labyrinthopeptins/labyrinthopeptin derivatives/combinationsof the present invention may also be administered rectally, for examplein the form of suppositories; or percutaneously or topically, forexample in the form of ointments, solutions or tinctures; or in otherways, for example in the form of aerosols or nasal sprays.

The pharmaceutical compositions according to the invention are preparedin a manner known per se and familiar to one skilled in the art. Forexample, pharmaceutically acceptable inert inorganic and/or organiccarrier substances and/or additives being used in addition to thelabyrinthopeptin(s) of the present invention and/or the labyrinthopeptinderivative(s) and/or combinations of the present invention in anystereochemical form, or a mixture of any stereochemical forms in anyratio, or a pharmaceutical acceptable salt thereof, as described above.For the production of pills, tablets, coated tablets and hard gelatincapsules it is possible to use, for example, lactose, corn starch orderivatives thereof, talc, stearic acid or its salts, etc. Carriersubstances for soft gelatin capsules and suppositories are, for example,fats, waxes, semisolid and liquid polyols, natural or hardened oils,etc. Suitable carrier substances for the production of solutions, forexample injection solutions, or of emulsions or syrups are, for example,water, saline, alcohols, glycerol, polyols, sucrose, invert sugar,glucose, vegetable oils, etc. Suitable carrier substances formicrocapsules, implants or rods are, for example, copolymers of glycolicacid and lactic acid.

Herein the term “effective dose” refers to an amount effective, atdosages and for periods of time necessary, to achieve the desiredanti-viral activity, i.e. the desired prophylactic/therapeutic result(i.e. prevention and/or treatment of the virus infections describedabove). An effective amount of the herein provided labyrinthopeptin, theherein provided labyrinthopeptin derivative, the herein providedcombination or the herein provided pharmaceutical compositions may varyaccording to factors such as the disease state, age, sex, and weight ofthe individual. Thus, the dosage regimen may be adjusted to provide theoptimum prophylactic/therapeutic response. An effective amount is alsoone in which any toxic or detrimental effects of the compound areoutweighed by the prophylactic/therapeutic beneficial effects. For anyparticular subject, specific dosage regimens may be adjusted over timeaccording to the individual need and the professional judgment of theperson administering or supervising the administration of thecompositions.

For example, the pharmaceutical compositions of the present inventionmay contain about 0.5 to about 90% by weight of the herein providedlabyrinthopeptin, the herein provided labyrinthopeptin derivative, orthe herein provided combination and/or their physiologically acceptablesalts and/or their prodrugs. The amount of the active ingredient (i.e.of the herein provided labyrinthopeptin, the herein providedlabyrinthopeptin derivative, or the herein provided combination) in thepharmaceutical compositions provided herein may be from about 0.5 toabout 1000 mg, preferably from about 1 to about 500 mg.

The dose of the active ingredients provided herein (i.e. of the hereinprovided labyrinthopeptin, the herein provided labyrinthopeptinderivative, or the herein provided combination) can vary within widelimits and, as is customary and is known to the physician, is to besuited to the individual conditions in each individual case. It depends,for example, on the specific compound employed, on the nature andseverity of the disease to be treated, on the mode and the schedule ofadministration, or on whether an acute or chronic condition is treatedor whether prophylaxis is carried out. An appropriate dosage can beestablished using clinical approaches well known in the medical art. Forexample, the daily dose for achieving the desired results (e.g. in anadult weighing about 75 kg) may be from about 0.01 to about 100 mg/kg,preferably from about 0.1 to about 50 mg/kg, in particular from about0.1 to about 10 mg/kg, (in each case in mg per kg of body weight). Thedaily dose can be divided, in particular in the case of theadministration of relatively large amounts, into several, for example 2,3 or 4, part administrations. As usual, depending on individual behaviorit may be necessary to deviate upwards or downwards from the daily doseindicated.

In the context of the present invention the concentration of the hereinprovided labyrinthopeptin, labyrinthopeptin derivative or combinationwithin the body of the subject (i.e. the patient) to be treated may notexceed 50 μM. It is envisaged that after administration of the hereinprovided labyrinthopeptin/labyrinthopeptin derivative/combination orpharmaceutical composition the concentration of said labyrinthopeptin,labyrinthopeptin derivative, or combination within the body of thesubject (i.e. the patient) is between 0.125 μM and 50 μM, preferablybetween 0.5 μM and 50 μM. This applies in particular if thelabyrinthopeptin is LabyA1 or if the labyrinthopeptin comprised in thelabyrinthopeptin derivative is LabyA1.

It is envisaged that in the subject to be treated the concentration ofthe herein provided labyrinthopeptin, labyrinthopeptin derivative orcombination is lower than the cytotoxic concentration of the respectivecompound. For determining the cytotoxic concentration (CC50) of thelabyrinthopeptin, labyrinthopeptin derivative or combination as providedherein the following assay may be applied.

Cells (e.g. HEp-2 cells), which stably express the reporter gene of afirefly luciferase (FF-luc), may be seeded in a 96-well plate in media,e.g. in Gibco® Advanced MEM. After 72 h of incubation at 37° C. in thepresence of increasing concentrations of the labyrinthopeptin,labyrinthopeptin derivative or combination to be tested (e.g. up to 100μM), the cells may be lysed and the extinction of the FF-luc (RLU) maybe measured. Therefore, a plate luminometer (Berthold) may be used. Thenumber of surviving cells is indirectly proportional to residualluciferase expression.

In addition to the active ingredient (i.e. of the herein providedlabyrinthopeptin, the herein provided labyrinthopeptin derivative, orthe herein provided combination) and to a carrier and/or a diluent, thepharmaceutical compositions of the present invention can contain one ormore additives such as, for example, fillers, disintegrants, binders,lubricants, wetting agents, stabilizers, emulsifiers, preservatives,sweeteners, colorants, flavorings, aromatizers, thickeners, buffersubstances, solvents, solubilizers, agents for achieving a depot effect,salts for altering the osmotic pressure, coating agents and/orantioxidants.

The terms “treatment”, “treating” and the like are intended to meanobtaining a desired pharmacologic (i.e. anti-viral) effect, e.g.,inhibiting viral entry or viral replication. It is envisaged that“treatment” and “treating” means that administration of the hereinprovided labyrinthopeptin, labyrinthopeptin derivative, combination orpharmaceutical composition to a subject (e.g. a human patient) resultsin a reduced number of virus-positive cells as compared to a controlsubject. Said control subject is a subject (e.g. a human patient) thatdid not receive said labyrinthopeptin, labyrinthopeptin derivative,combination or pharmaceutical composition. Thus, herein terms“treatment” or “treating” relate to a partial or complete cure of aninfection with the viruses as mentioned above. As described above,herein a “virus infection” or “viral infection” refers to an infectiousdisease, i.e. a disease/disorder that is caused by a viral infection.For example, said disease/disorder may be caused by the symptoms of aviral infection. The terms “treatment” or “treating” relate to anytreatment of a disease in a subject, particularly in a human; or in caseof VSV as well treatment of an animal, preferably cattle, pig or horses,and include inhibiting the disease (i.e. the viral infection), arrestingor slowing the development/progression of the disease (i.e. of the viralinfection); or relieving the disease (e.g., reducing symptoms associatedwith/caused by the viral infection). The terms “treatment” or “treating”also include the therapeutic intervention of an asymptotic viralinfection, e.g. an asymptotic viral infection with HCV, ZIKV or CMV.Treating an asymptotic viral infection includes, e.g., reducing theamount of virus-positive cells, the amount of virus particles and/orviral replication within the infected subject. The terms “prevention”,“preventing” and the like mean that a prophylactic effect is obtained interms of completely or partially preventing a virus infection or asymptom thereof. It is preferred that the herein providedlabyrinthopeptin/labyrinthopeptin derivative/combination/pharmaceuticalcomposition is used to treat an existing viral infection (and not toprevent the occurrence of a viral infection).

The above-mentioned “prevention” and/or “treatment” compriseadministration of the above-mentioned labyrinthopeptin/labyrinthopeptinderivative/combination/pharmaceutical composition in combination withone or more additional active/therapeutic agents, or in combination withany other therapy. The combination of prophylactic/therapeutic agentsand/or compositions may be administered or co-administered (e.g.,consecutively, simultaneously or at different times) in any conventionaldosage form. Co-administration in the context of the present inventionrefers to the administration of more than one therapeutic in the courseof a coordinated treatment to achieve an improved clinical outcome. Suchco-administration may also be coextensive, that is, occurring duringoverlapping periods of time. For example, a first agent may beadministered to a patient before, concomitantly, before and after, orafter a second active agent is administered. The agents may in an aspectof the invention be combined/formulated in a single composition and thusadministered at the same time. In another aspect of the invention, theactive agent(s) of the present invention is/are used/administered incombination with one or more agent(s) currently used to prevent or treatthe disorder in question. Accordingly, in an envisaged aspect of theinvention, the labyrinthopeptin/labyrinthopeptinderivative/combination/pharmaceutical composition of the invention isadministered/used in combination with an anti-viral therapy. Potentialanti-viral therapies that may be used in a co-therapy with the hereinprovided labyrinthopeptin/labyrinthopeptinderivative/combination/pharmaceutical composition are described hereinabove.

As used herein, the terms “subject” (also called “patient”) is taken tomean a warm blooded animal such as a mammal, for example, a camel, acat, a dog, a mouse, a guinea pig, a horse, a pig, cattle such as abovine cow, a sheep and a human. It is preferred that the subject is amammal. It is most preferred that the subject is a human. Particularly,in the case of an infection with VSV the subject may also be an animal,preferably cattle, a pig or a horse.

In context of the present invention, “identity”, “percent identity”, or“X % identical” means that amino acid sequences have identities of atleast 80%, preferably at least 85%, more preferably at least 90%, andeven more preferably at least 95% to the sequence of SEQ ID NO: 3; or atof least 80%, preferably at least 85%, more preferably at least 90%, andeven more preferably at least 94% to the sequence of SEQ ID NO: 4,wherein the higher identity values are preferred upon the lower ones. Inaccordance with the present invention, the term “identity/identities” or“percent identity/identities” in the context of two or more amino acidsequences, refers to two or more sequences that are the same, or thathave a specified percentage of amino acids that are the same (e.g., thathave at least 80%, preferably at least 85%, more preferably at least90%, and even more preferably at least 95% identity with the amino acidsequences of SEQ ID NO: 3; or that have at least 80%, preferably atleast 85%, more preferably at least 90%, and even more preferably atleast 94% identity to the sequence of SEQ ID NO: 4; and beingfunctional, wherein the function comprises anti-viral activity,preferably against RSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and/orHCV, when compared and aligned for maximum correspondence over a windowof comparison, or over a designated region as measured using a sequencecomparison algorithm as known in the art, or by manual alignment andvisual inspection.

Preferably the described identity exists over a region that is at leastabout 10 amino acids, preferably at least 15 amino acids, morepreferably at least 20 amino acids, and most preferably all amino acidsof SEQ ID NO: 3 or 4 in length.

Those having skills in the art will know how to determine percentidentity between/among sequences using, for example, algorithms such asthose based on CLUSTALW computer program (Thompson, 1994, Nucl AcidsRes, 2: 4673-4680) or FASTDB (Brutlag, 1990, Comp App Biosci, 6:237-245), as known in the art. Also available to those having skills inthis art are the BLAST and BLAST 2.0 algorithms (Altschul, 1997, NuclAcids Res 25: 3389-3402; Altschul, 1993, J Mol Evol, 36: 290-300;Altschul, 1990, J Mol Biol 215: 403-410). For example, BLAST 2.0, whichstands for Basic Local Alignment Search Tool BLAST (Altschul, 1997, loc.cit.; Altschul, 1993, loc. cit.; Altschul, 1990, loc. cit.), can be usedto search for local sequence alignments. BLAST, as discussed above,produces alignments of both nucleotide and amino acid sequences todetermine sequence similarity. Because of the local nature of thealignments, BLAST is especially useful in determining exact matches orin identifying similar sequences. Analogous computer techniques usingBLAST (Altschul, 1997, loc. cit.; Altschul, 1993, loc. cit.; Altschul,1990, loc. cit.) are used to search for identical or related moleculesin nucleotide databases such as GenBank or EMBL.

The present invention is further described by reference to the followingnon-limiting figures and Examples.

The Figures show:

FIG. 1. Chemical structure of (A) lanthionin and (B) labionin

FIG. 2. Chemical structure of dehydrobutyrate

FIG. 3. Chemical structure of LabyA1 and LabyA2 showing theirstereochemistry

FIG. 4. Chemical structures of LabyA1, LabyA2, LabyA1-Hexyn andLabyA2-Hexyn

FIG. 5. Dose-dependent inhibition of CMV infection by Labyrinthopeptins.GFP signals (relative units+/−SD) of cultures of NHDF cells(triplicates) infected with a GFP-expressing CMV (i.e. HCMV) strain andtreated with the indicated concentrations of Labyrinthopeptins A1 and A2were measure at day 4 post infection. The IC50 values of the substanceswere calculated using Graphpad Prism nonlinear fit log (inhibitor) vs.response (three parameters) analysis. One representative result of twoexperiments is shown.

FIG. 6. Labyrinthopeptins inhibit CMV infection in an early phase. NHDFcells were infected with a GFP-expressing CMV strain and test compoundswere added at the indicated time points. At 96 hpi the GFP expression incells of infected cultures (triplicates) was measured. Theconcentrations of Laby A1 and A2 were 3 μM and 7 μM, respectively. Dataare means (+/−SD) of values measured in triplicate cultures.Representative data from one of two experiments are shown.

FIG. 7. Mode of action of Labyrinthopeptins. CMV particles or NHDF cellswere preincubated with Labyrinthopeptins, PAA or DMSO for 1 h orremained untreated. The media of the samples were then diluted 16-fold,below the concentration of Labyrinthopeptins found to be effective inprevious experiment, followed by CMV inoculation for 3 h and finallyreplacement with new medium. For control cultures were permanentlytreated with an effective dose of the substances or 16-fold dilutedconcentrations. EGFP expression of the cells (means from fivereplicates) was measured at 4 d p.i. The experiment was repeated 3 timeswith similar results.

FIG. 8. Scheme depicting the design of the TOA experiment.

FIG. 9. Outline of the Mode of action assay.

FIG. 10. Synergisitc effects of Labyrinthopeptins A1 and A2 on DENVinfection. Huh-7 cells were incubated in the presence of varyingconcentrations of Laby and after 30 min subjected to DENV. 48 hpost-infection the number of DENV-positive cells was determined byevaluating DENV-envelope protein expression(AlexaFluor488-immunostained) via high-content fluorescence imaging. Thenumber of total cells was determined by evaluating DAPI-stained nuclei.IC₅₀-values indicate that LabyA1 (IC₅₀=3.7 μg/ml) is a more potentinhibitor of viral infection than LabyA2 (IC50=15.4 μg/ml). When LabyA1and LabyA2 were applied in a 1:1 combination, their anti-viral activityis further improved (IC₅₀=2.6 μg/ml). (Values are ±SEM; n=5)

FIG. 11. Laby-Hexyn derivatives retain the anti-DENV activity. Huh-7cells were incubated in the presence of varying concentrations ofLaby-Hexyn derivatives and after 30 min subjected to DENV. 48 hpost-infection the number of DENV-positive cells was determined byevaluating DENV-envelope protein expression(AlexaFluor488-immunostained) via high-content fluorescence imaging. Thenumber of total cells was determined by evaluating DAPI-stained nuclei.IC₅₀-values indicate that Laby-Hexyn derivatives retain their anti-DENVactivity: IC₅₀(LabyA1-Hexyn)=3.7 μg/ml, IC₅₀(LabyA2-Hexyn)=14.2 μg/ml,IC₅₀(1:1 combination of LabyA1-Hexyn/LabyA2-Hexyn)=2.0 μg/ml. (valuesare ±SEM; n=3)

FIG. 12. Dipolar cycloaddition of Biotin-Azide to immobilized Laby-Hexynderivatives in vitro. 2 μg of Laby-derivatives were immobilized on aNunc Maxisorp 96 well plate. After blocking with 1% BSA in PBS reactionmix for dipolar cycloaddition with or without Biotin-azide was appliedfor 2 h. Subsequently success of the reaction was checked by incubatingwells with Avidin-labeled HRP for 1 h followed by a color reactioninduced by addition of substrate solution C [BioLegend]. Color reactionwas stopped by addition of 50 μl H₃PO₄ (1 M) and OD_(450 nm) wasmonitored. (Values are ±SEM; n=2)

FIG. 13. Schematic representation of the screening system of Example 4.

FIG. 14. Assay validation of the screening system of Example 4. Cellsurvival is assessed by staining with crystal violet.

FIG. 15. Assay validation of the screening system of Example 4. Cellsurvival in the presence of RSV and ribavirin is shown.

FIG. 16. Labyrinthopeptins inhibit RSV induced cell death and RSVinfection. A: Cell survival in the presence of RSV and LabyA1; B: cellsurvival in the presence of RSV and LabyA2. C: Labyrinthopeptins inhibitRSV infection.

FIG. 17. A: Characterization of the susceptibility of the chikungunyavirus glycoprotein-mediated and the VSV-glycoprotein-mediated cell entryprocess to pharmacological and immunological inhibition and cellularrestriction. B: Labyrinthopeptin A1.

FIG. 18. Effects of labyrinthopeptins on TBEV infection.

FIG. 19. Effects of labyrinthopeptins on ZIKV infection.

FIG. 20. Effects of labyrinthopeptins on HCV infection. A:Labyrinthopeptin A1 antiviral activity against HCV JcR2a. B:Labyrinthopeptin A2 antiviral activity against HCV JcR2a.

FIG. 21. Cytotoxic concentration (CC50) of Labyrinthopeptin A1 and A2.

The Examples illustrate the invention.

EXAMPLE 1: MATERIALS AND METHODS Dose Response Assay

The antiviral assay is based on the inhibition of CMV-driven GFPexpression in NHDF cells. Briefly, NHDF cells (˜1.6×10⁴ per well) wereseeded in 96-well plates 1 day prior to infection. Variousconcentrations of Labyrinthopeptin A1 (final conc. 10, 5, 2, 1 and 0.5μM) and Labyrinthopeptins A2 (final conc. 15, 10, 5, 2 and 1 μM) weredispensed to the cells to a total volume of 200 μl/well in triplicates.PAA (180 μM) was added as positive control. DMSO was added to eitherinfected cells or uninfected cells with the highest concentration asdone with the substances added to cells, as a control for substanceswhich were diluted in DMSO. After 1 h of incubation, the GFP-expressingCMV (i.e. HCMV) strain pHG-1 (Borst, J. Virol. 2005 (79): 3615-26;herein called HT8-GFP), which is based on the CMV (i.e. HCMV) laboratorystrain AD169, was added to cells at an MOI of 0.5 and cells wereincubated for another 4 days. At 4 dpi the media were removed from thewells and cells were fixed with 3% PFA and washed with PBS followed byadding PBS before measurement. GFP expression from the cells wasmeasured using a BioTek Synergy 2; the protocol for excitationwavelength was set to 485/20 nm and the emission wavelength was 516/20nm.

Time-of-Drug-Addition (TOA) Experiment

The TOA experiment was performed using 1.6×10⁴ NHDF cells per well in 96well plates. Labyrinthopeptin A1 (3 μM), A2 (7 μM), DMSO (0.1%) or PAA(180 μM) were added to the cultures at −1, 0, 1, 3, 6, 24, 48, 72 hoursof addition of the virus. Cells were infected with HT8-GFP at amultiplicity of infection (MOI) of 0.5 at 0 h. At 96 hpi GFP expressionof cells was measured above.

Mode of Action Assay

8×10³ PFU of the HT8-GFP expressing AD169 strain and 1.6×10⁴ NHDFcells/well were pre-incubated with 3 μM and 7 μM of TOA LabyA1 and A2,respectively for 1 h and then diluted 16-fold before adding them tocells or infecting with virus in 5 wells. The media was replaced withnew media after 3 h of incubation and for controls, viruses and cellswere pre-incubated with DMSO (highest concentration of substances) andPAA (180 μM) for 1 h followed by diluting them 16-fold and adding towells for 3 hours, and then exchanged with new media.

Dose-Dependent Effects of Labyrinthopeptins on KSHV Infection

3×10⁴ HEK 293 cells were seeded in growth medium (DMEM; 10% FBS) onto a96 well plate and incubated for 24 h at 37° C. and 5% CO₂. After removalof the medium, 180 μl growth medium together with 20 μl of a solution ofKSHV (produced from cell line BJAB-rKSHV (Kati, J Virol. 2013,87(14):8004-16; Kati, J Virol Methods. 2015; 217:79-86) at an MOI of0.01 were applied to each well. Simultaneously the indicated amounts ofLabyA1 or LabyA2 were added. After 48 h of incubation, the GFPexpressing HEK 293 cells were counted under a fluorescence microscope.The data points given in the figures are means of triplicates. Theresults are shown in Table 4, below.

Dose Response Assay

Huh-7.5 cells (3×10⁴ per well) were seeded in black 96-welloptical-bottom plates [Nunc] in full growth medium one day prior toinfection. After washing with PBS, 40 μl assay medium (5% FBS) was addedto cells containing either Laby A1, Laby A2 (final conc. 50, 16.7, 5.56,1.85, 0.62, 0.21, 0.069 μg/ml) or a combination of Laby A1 and Laby A2(25, 8.3, 2.8, 0.93, 0.31, 0.10, 0.034 μg/ml each). Treatments were runin doublets. PBS served as a control. After 30 min of incubation, cellswere infected with Dengue Virus (Type 2 New Guinea C) at an MOI of 0.5to give a final volume of 60 μl/well. After 2 h incubation at roomtemperature cells were washed with PBS and 100 μl assay medium was addedper well. Infected cells were incubated for another 48 h. Hereaftermedia were removed from the wells and cells were fixed with 4% PFA.Fixed cells were washed extensively with PBS and permeabilized with0.25% TritonX-100 for 5 min. After blocking with 5% FB in PBS primaryantibody was applied (Anti-Dengue Virus E glycoprotein antibody [DE1](ab41349) [Abcam], 1:100 diluted in 5% FBS/PBS) for 2 h. After washingsecondary antibody (Alexa Fluor® 488 Goat Anti-Mouse IgG (H+L) [LifeTechnologies], 1:1000 diluted in 5% FBS/PBS) was applied for 1 h.Finally, cells were stained with DAPI (500 ng/ml in PBS) for 5 min.

Fluorescent cells were analyzed by high-content imaging using theautomated microscope ImageXpressMicro [Molecular Devices] and theMetaXpress-software. The excitation wavelengths were set to 360 nm(DAPI) and 485 nm (Alexa Fluor488) and the emission wavelengths were setto was 460 nm (DAPI) and 516 nm (Alexa Fluor488). Images of sixsites/well were acquired (2 columns, 89 μm spacing; 3 rows, 67 μmspacing). The number of total cells/site was determined by automaticallycounting DAPI-stained nuclei. The percentage of DENV-positive cells wascalculated by automatically evaluating the number of Alexa Fluor488-positive cells in relation to the total cell number. Values obtainedfrom the six sites were averaged and plotted onto a semi-logarithmicX/Y-chart. IC50-values were calculated by non-linear regression.

Synthesis of Laby A1-Hexyn Derivative

To a solution of 2-chloro-4,6-dimethoxy-1,3,5-triazine (1 mg, 0.006mmol) in dimethylformamide (1 ml), n-methylmorpholine (2 μL, 0.015 mmol)was added at room temperature. After 1 h stirring at room temperature,5-Hexynoic acid (0.5 μL, 0.004 mmol) was added. After 30 minutes ofstirring, Labyrinthopeptin A1 (6 mg, 0.003 mmol) was added to thereaction mixture and allowed to stir for 16 h at room temperature. Thereaction mixture was purified by reversed-phase HPLC using a Gemini 5μC18 column (dimension: 250 mm×20 mm) with acetonitrile in water (10-90%)with 0.1% HCOOH as eluents. Peaks were fractionated based on the UVdetection at 220 nm. Collected desired compound was lyophilized to yield2 mg (31.7%). The product was characterized by high resolution massspectrometry.

HRMS (Q-tof): Calculated for C₉₈H₁₂₆N₂₃O₂₆S₄ [M+H]⁺ 2168.8127, found2168.7821.

Synthesis of Laby A2-Hexyn Derivative

To a solution of 2-chloro-4,6-dimethoxy-1,3,5-triazine (1 mg, 0.006mmol) in dimethylformamide (1 ml), n-methylmorpholine (2 μL, 0.015 mmol)was added at room temperature. After 1 h at room temperature 5-Hexynoicacid (0.5 μL, 0.004 mmol) was added. After 30 minutes of stirring,Labyrinthopeptin A2 (6 mg, 0.003 mmol) was added to the reaction mixtureand allowed to stir for 16 h at room temperature. The reaction mixturewas purified by reversed-phase HPLC using a Gemini 5μ C18 column(dimension: 250 mm×20 mm) with acetonitrile in water (10-90%) with 0.1%HCOOH as eluents. Peaks were fractionated based on the UV detection at220 nm. Collected desired compound was lyophilized to yield 1.5 mg(23.8%). The product was characterized by high resolution massspectrometry.

HRMS (Q-tof): Calculated for C₉₁H₁₁₇N₂₀O₂₅S₄ [M+H]⁺ 2017.7381, found2017.7376.

Dipolar Cycloaddition of Biotin-Azide to Immobilized Laby-HexynDerivatives

All subsequent washing steps were performed with three times with 200 μlof PBS. 2 μg of either LabyA1-Hexyn, LabyA2-Hexyn or LabyA1 were dilutedin Coating Buffer A [BioLegend] and adsorbed in triplets for 16 h at 4°C. to a 96 well plate (Nunc Maxisorp). After washing with PBS wells wereblocked with 1% BSA (w/v) in PBS (blocking buffer) for 1 h at roomtemperature. Wells were again washed with PBS and 100 μl cycloadditionreaction mix (2 mM CuSO₄, 5 mM Sodium ascorbate, 100 μM Biotin-azide[Azide-PEG3-Biotin conjugate, Sigma], diluted in blocking buffer) wereapplied. Cycloaddition reaction mix without Biotin-Azide served as acontrol. The reaction was performed for 2 h at room temperature. Afterwashing with PBS, wells were incubated with 100 μl blocking solutioncontaining Avidin-labeled Horse radish peroxidase (HRP) [BioLegend] for1 h. Finally wells were washed with PBS and 100 μl substrate solution C[BioLegend] was applied to each well. Color reaction was stopped after15 min by addition of 50 μl H₃PO₄ (1 M). OD_(450 nm) was determinedusing an automated plate reader [Biotek].

Chikungunya Virus Assay

HEK293T cells were seeded into a 96-well plate (2×10⁴ cells/well) andcultured under standard conditions. On the next day VSV-G- and CHIKVgp-pseudotyped lentiviral particles encoding luciferase were treatedwith indicated concentrations of Labyrinthopeptin A1 or DMSO. Cells weretransduced with Labyrinthopeptin A1-treated or DMSO-treated vectorparticles and cultured for 48 h. Afterwards, luciferase activity intransduced cells was measured luminometrically. IC50 values werecalculated using GraphPad Prism 5; see Example 5 and FIG. 17.

EXAMPLE 2: EFFECT OF LABYRINTHOPEPTINS A1 AND A2 ON CMV INFECTIONDose-Dependent Effects of Labyrinthopeptins on CMV Infection

To determine a potential effect of Labyrinthopeptins on CMV (i.e. HCMV)infection, cultures of normal human dermal fibroblasts (NHDF) weretreated with various concentrations of Labyrinthopeptins A1 and A2 onehour before infection with a GFP-expression CMV strain at a multiplicityof infection of 0.5 PFU/cell. 4 days later GFP expression of the cellswas measured as readout for viral gene expression. DMSO-treated cells(DMSO is the diluent for the Labyrinthopeptins) and untreated cellsserved as positive controls for the infection, and non-infected cells asnegative control. Treatment of infected cell cultures withphosphonoacetic acid (PAA) was used a positive control for inhibition ofviral replication.

The Labyrinthopeptins inhibited virus-driven GFP expression in cellsinoculated with CMV in a dose-dependent manner (FIG. 5). The IC50 valuesfor Labyrinthopeptins A1 and A2 were approximately 1.3 and 5.4 μM,respectively.

Time Point of the Inhibitory Effect of Labyrinthopeptins During the LifeCycle of CMV

To get an idea on which phase of the CMV infection cycle theLabyrinthopeptins exert their effect, a time-of-addition experiment wasperformed. Labyrinthopeptins A1 and A2 (at a final concentration of 3and 7 μM, respectively) were added to the cell cultures, either before,concomitantly or subsequently to inoculation with CMV (see FIG. 6). GFPexpression as a readout for successful viral infection was measured atday 4 p.i. DMSO-treated cultures served as controls.

The strongest inhibition of viral gene expression (almost completeinhibition) was observed when the substances were added before orconcomitantly with virus inoculation of the cultures. About 50%inhibition occurred when the compounds were added 1 h post inoculationand approximately 25% inhibition upon addition at 3 and 6 h p.i. Atlater times points viral infection could be inhibited only minimally.

These results suggest that the labyrinthopeptins act on an early step ofviral infection or possibly directly on viral particles. One has topoint out that in the experiment shown, entry of CMV into the cells isnot synchronized. Although a substantial portion of the inoculated virushas entered the cells one hour p.i., other particles could remainattached to the cell surface and enter the cells only subsequently.

Putative Effect of Labyrinthopeptins A1 and A2 on Virus Particles

To learn whether the substances act primarily on the virus particles oron cells, pretreatment was performed using concentrations ofLabyrinthopeptins A1 and A2 3 μM and 7 μM of LabyA1 and A2,respectively) that in the previous experiments were found to beeffective (>98% inhibition of infection).

Following incubation for 1 h the virus sample or the medium in the cellcultures were diluted 16-fold, resulting in a concentration of thecompounds which according to the dose-response curve (cf. FIG. 5) wouldnot exert an effect. Pretreated virus was then added to cells (FIG. 7,group “virus pretreated”) or untreated virus was added to pretreatedcells (FIG. 7, group “cells pretreated”), followed by incubation for 3 hand replacement of the inocula with new media. GFP expression wasdetermined at 96 h p.i. In parallel, cultures were treated with theeffective doses of the compounds or 16-fold diluted concentrationsconcomitantly with CMV inoculation to verify inhibition by the compoundsand loss upon 16-fold dilution (FIG. 7, dilution). PAA and DMSO wereused as controls.

Upon pretreatment of viruses with Labyrinthopeptins A1 and A2, viralgene expression was inhibited by ˜50% and ˜90%, respectively. Basicallyno inhibition was observed upon pretreatment of cells. Treatment ofinfected cells throughout the infection cycle with high concentrationsof Labyrinthopeptins A1 and A2 resulted in nearly 100% inhibition asexpected (FIG. 7, group “permanently treated, effective dose), whereasonly slight inhibition was seen following permanent treatment with the16-fold diluted concentration (FIG. 7, group “permanently treated,16-fold dilution”). PAA—as a soluble substance that acts on the viralDNA polymerase at a later stage of infection—exerted inhibition onlywhen permanently present in the culture medium (to a lesser extent whenthe 16-fold diluted concentration was applied as expected), but not whenit was removed after pretreatment of the virus or cells.

The results suggest that the labyrinthopeptins act primarily on thevirus particles. The somehow reduced inhibitory effect upon pretreatmentwith Labyrinthopeptin A1 compared to the effect seen upon permanenttreatment could either indicate that the inhibition is partiallyreversible or that the substance is additionally effective during thecell attachment or entry phase of CMV.

EXAMPLE 3: EFFECTS OF LABYRINTHOPEPTINS A1 AND A2 ON DENV INFECTIONSynergisitc Effects of Labyrinthopeptins A1 and A2 on DENV Infection

To determine a potential synergistic effect of Labyrinthopeptins A1 andA2 on DENV-infection a dose response assay was performed. Cultures ofHuh-7.5 cells (human hepatocarcinoma cell line) were treated withvarious concentrations of either Laby A1, LabyA2 or an equivalentcombination of LabyA1 and LabyA2 for 30 min. Cells were subsequentlyinfected with DENV (Type 2 New Guinea C) at a MOI of 0.5 PFU for 2 h atroom temperature. Unbound viral particles were removed and infectedcells were incubated for 48 h. Hereafter cells were fixed using 4% PFAin PBS and immunostained for DENV envelope protein expression. For thispurpose, a combination of anti-Dengue Virus E glycoprotein antibody andan Alexa Fluor 488-conjugated secondary antibody was applied.Additionally cell nuclei were stained with DAPI. The number of totalcells as well as the percentage of Alexa Fluor 488-positive cells (=DENVpositive cells) was determined by high-content fluorescence imaging.

IC₅₀-values indicate that LabyA1 (IC₅₀=3.7 μg/ml) is a more potentinhibitor of viral infection than LabyA2 (IC₅₀=15.4 μg/ml). When LabyA1and LabyA2 were applied in a 1:1 combination, their anti-viral activityis further improved (IC₅₀=2.6 μg/ml) (FIG. 10).

Laby-Hexyn Derivatives Retain the Anti-DENV Activity

To conduct mode of action studies we generated Laby-derivatives carryingan N-terminal Hexyn-group. These can further be derivatized in vitro andin vivo by dipolar cycloaddition e.g. of an azide-labeled fluorophore.To determine the biological activity of Laby-Hexyn derivatives onDENV-infection a dose response assay was performed as depicted above.The IC₅₀-values obtained are similar to the IC₅₀-values obtained foruncoupled Laby and thus indicate that Laby-Hexyn derivatives retaintheir anti-DENV activity: IC₅₀(LabyA1-Hexyn)=3.7 μg/ml,IC₅₀(LabyA2-Hexyn)=14.2 μg/ml, IC₅₀(1:1 combination ofLabyA1-Hexyn/LabyA2-Hexyn)=2.0 μg/ml (FIG. 11).

Dipolar Cycloaddition of Biotin-Azide to Immobilized Laby-HexynDerivatives

To test whether the dipolar cycloaddition works in vitro with Laby-Hexynderivatives, these were immobilized on 96 well plate (Nunc Maxisorp). 2μg of either LabyA1-Hexyn, LabyA2-Hexyn or LabyA1 were diluted inCoating Buffer A [BioLegend] and adsorbed in triplets to one well of the96 well plate for 16 h at 4° C. Cycloaddition reaction of Biotin-azidewas performed as given in material and methods. Cycloaddition reactionmix without Biotin-Azide served as a control.

The data demonstrate that the dipolar cycloaddition of Biotin-azide toimmobilized Laby-Hexyn derivatives works well indicated by thepronounced OD_(450 nm). In contrast, dipolar cycloaddition does not workwith non-alkynylated Laby (FIG. 12).

EXAMPLE 4: EFFECTS OF LABYRINTHOPEPTINS A1 AND A2 ON RSV INDUCED CELLDEATH AND RSV INFECTION Labyrinthopeptins A1 and A2 Inhibit RSV InducedCell Death

A cell-based screening system was used to determine the antiviral effectof labyrinthopeptin A1 and A2 against the human respiratory syncytialvirus (RSV, also called hRSV). A schematic representation of thescreening system is depicted in FIG. 13.

HEp-2 cells, which are stably expressing the reporter gene of a fireflyluciferase (FF-luc), were seeded in a 96-well plate in 200 μlappropriate media. The incubation time has been set to 72 h at 37° C.with a MOI of 3 to obtain a useful measuring window between uninfectedand infected cells. After 72 h the cells have been lysed and theluminescence produced by the FF-luc was measured using a plateluminometer (in RLU). The cells were infected by RSV in the presence ofdifferent concentrations of labyrinthopeptin A1 and A2. RSV is a lyticvirus and kills infected cells. Therefore, unrestricted infection andspread of RSV will lead to cell death and as a result of this, decreaseof luciferase gene expression. The number of surviving cells isindirectly proportional to the virus infection/replication efficiency.In other words, the more cells survive, the less RSV was able to infectcells. Cell survival can be assessed and quantified either bydetermination of total viable cells (e.g. by staining with crystalviolet, which stains remaining cells; compare FIG. 14). Moreover, cellsurvival is proportional to residual luciferase expression. To validateour assay, we used ribavirin, a guanosine nucleoside analogue, which isknown to inhibit RSV replication in cell culture (FIG. 15). The halfmaximal inhibitory concentration (IC₅₀) has been calculated forlabyrinthopeptin A1 IC₅₀=3.87 μM in 6 independent experiments (FIG. 16A)and for labyrinthopeptin A2 IC₅₀=47.93 μM in 3 independent experiments(FIG. 16B).

Labyrinthopeptins A1 and A2 Inhibit RSV Infection

Wild-type RSV (i.e. hRSV) infection and intracellular RSV-P staining wasused to determine IC50 of labyrinthopeptin A1 and A2 (see FIG. 16 C).

Therefore, 1×10⁵ HEp 2 cells seeded in a 12-well plate were inoculatedfor 4 h with the wild-type RSV at a multiplicity of infection (MOI) of 1on a horizontal shaker. Inoculation was done together with differentconcentrations of labyrinthopeptin A1 or A2. After 4 h the cells werewashed with sterile PBS and incubated at 37° C. 18 hours post infectionthe cells were detached by trypsinization and fixed in fixation buffer(0.5% paraformaldehyde, 1% fetal calf serum [FCS] in phosphate-bufferedsaline [PBS]) for 30 min at 4° C. Subsequently, the cells werepermeabilized with a saponin-containing permeabilization buffer (0.1%saponin, 1% FCS in PBS) for 20 min at 4° C. Afterwards, the cells werestained for 30 min at 4° C. with an RSV-P-specific antibody (26D6G5C6)diluted 1:500 in permeabilization buffer. Subsequently, the cells werewashed with PBS, and bound antibodies were detected by incubation for 30min at 4° C. with mouse-specific Alexa 488 secondary antibodies (ThermoFisher Scientific) at a 1:200 dilution in permeabilization buffer. Thestained cells were washed twice with PBS and analyzed using an Accuri C6and FlowJo software.

The half maximal inhibitory concentrations (IC50) have been calculatedfor labyrinthopeptin A1 IC50=0.39 μM and for labyrinthopeptin A2IC50=4.97 μM (see FIG. 16 C).

EXAMPLE 5: CHARACTERIZATION OF THE SUSCEPTIBILITY OF THE CHIKUNGUNYAVIRUS (CHIKV) GLYCOPROTEIN-MEDIATED AND STOMATITIS INDIANA VIRUS (VSV)GLYCOPROTEIN-MEDIATED CELL ENTRY PROCESS TO PHARMACOLOGICAL ANDIMMUNOLOGICAL INHIBITION AND CELLULAR RESTRICTION

Here, use is made of lentiviral vectors carrying CHIKV glycoproteins E1and E2 or VSV glycoprotein on their surface for studying properties ofthe CHIKV or VSV glycoprotein-mediated entry process and theirsusceptibility to pharmacological and immunological inhibition, as wellas to restriction by cellular antiviral IFITM proteins. Treatment of293T cells with Labyrinthopeptin A1 resulted in dose-dependent reductionof transduction efficiency upon challenge with CHIKVglycoprotein-expressing pseudotypes, yielding an IC50 value between0.5-1.7 μM; see FIG. 17. Introduction of sublineage-specific mutationsin CHIKV glycoproteins did not grossly modulate the entry efficiency oflentiviral vectors, and all variants remained susceptible toneutralization by a monoclonal antibody targeting CHIKV E2. Thecapability of cellular IFITM proteins to restrict CHIKVglycoprotein-mediated cell entry of lentiviral vectors was interrogatedin 293T cell lines stably expressing individual C-terminal HA-taggedhuman IFITM proteins. Interestingly, expression of IFITM1-HA, IFITM2-HAand IFITM3-HA on target cells resulted in a 2-fold reduction oftransduction efficiency, respectively, as compared to vector-expressingcells. The necessity of appropriate post-translational modification ofIFITM proteins, including palmitoylation and ubiquitination of conservedresidues, for their antiviral activity, as well as thespecies-specificity of IFITM proteins' antiviral capacity are currentlyinvestigated. Interestingly, selected CHIKV glycoprotein variants seemto display increased susceptibility to IFITM protein-mediatedrestriction.

The VSV glycoprotein-mediated entry process as well as itssusceptibility to inhibition by Labyrinthopeptin A1 was analyzed in thesame manner as described for CHIKV, above. Treatment of 293T cells withLabyrinthopeptin A1 resulted in dose-dependent reduction of transductionefficiency upon challenge with VSV glycoprotein-expressing pseudotypes,yielding an IC₅₀ value as shown in FIG. 17.

EXAMPLE 6: EFFECTS OF LABYRINTHOPEPTINS ON TBEV INFECTION

1.5×10⁴ Vero-B4 cells were seeded in growth medium (DMEM; 10% FBS) ontoa 96 well plate and incubated for 24 h at 37° C. and 5% 00₂. Afterremoval of the medium, LabyA1, Laby A2 or a 1:1 mixture of LabyA1/LabyA2was added to the cells in 26.5 μl medium. After 30 min of incubation at37° C., cells were infected with TBEV (Toro isolate) at a MOI of 0.01for 1 h. In the resulting total volume of 64 μl per well, topconcentration of Laby was 50 μg/ml with serial 3-fold dilutions down to0.07 μg/ml being applied. After removal of the inoculum, infected cellswere cultivated for 3 days in a mixture of Avicel and DMEM. Eventually,infected cells were fixed with 6% Formaldehyde. After permaebilizationwith TritonX, TBEV-envelope protein was detected by respective primaryand HRP-linked secondary antibodies. The enzymatic reaction wasperformed using TrueBlue Peroxidase substrate. Pictures of cell cultureplates were taken with the ChemiDoc Imaging System [BioRad]; see FIG.18. IC₅₀ values were estimated by visual inspection of the wells. In thepicture, areas of infection appear black and non-infected areas appearwhite; see FIG. 18.

The IC₅₀ values for LabyA1 were 24.10 μM and 50 μg/ml, respectively; theIC₅₀ values for LabyA2 were >25.99 μM and >50 μg/ml, respectively; andthe IC₅₀ values for the combination of LabyA1 and LabyA2 were 8.34 μMand 16.67 μg/ml, respectively; see Table 4.

EXAMPLE 7: EFFECTS OF LABYRINTHOPEPTINS A1 AND A2 ON ZIKV INFECTION

Cultures of Huh-7.5 cells (human hepatocarcinoma cell line) were treatedwith various concentrations of either LabyA1, LabyA2 or an equivalentcombination of LabyA1 and LabyA2 for 30 min. Cells were subsequentlyinfected with ZIKV (Strain MR766-NIID) at a MOI of 0.5 PFU for 2 h atroom temperature. Unbound viral particles were removed and infectedcells were incubated for 48 h. Hereafter viral RNA was isolated from thecell culture supernatant (150 μl) using the NucleoSpin® 96 Virus Kit[Macherey-Nagel] according to the vendor's manual. RNA was quantified byabsorbance and 2.5 μg were reversely transcribed via RevertAid ReverseTranscriptase [Thermo] with RT-Primer [5′-GGTTTCCCAGCTTCTCCTGG-3′]. 100ng of reverse transcribed RNA were subjected to SYBR-green basedquantitative RT-PCR using the LightCycler®480 with LightCycler®480 SYBRGreen I Master [Roche] and a ZIKV-specific forward and reverse primerpair (5′-AAAAACCCCATGTGGAGAGG-3′ and 5′-CATTCCTTCAGTGTGTCACC-3′,respectively). The absolute number of ZIKV-genome copy equivalents (GCE)was determined via standard curves generated from plasmids with knownconcentrations carrying the respective amplified fragment of the ZIKVgenome. Values are ±SEM; n=4. LabyA1 (IC₅₀=4.6 μg/ml); LabyA2 (IC₅₀=5.4μg/ml); combination LabyA1 and LabyA2 (IC₅₀=3.5 μg/ml).

EXAMPLE 8: EFFECTS OF LABYRINTHOPEPTINS A1 AND A2 ON HCV INFECTION

Huh 7.5 Firefly luciferase expressing cells (Huh 7.5 Fluc) cells wereseeded in 96 well plates (10*10³ cells/well) and incubated overnight (18hours approx) at 37° C. with 5% CO₂ supply. Huh 7.5 Fluc cells are ahepatoma cell line stably expressing firefly luciferase protein which isused to measure cell viability.

The following day, labyrinthopeptin at various concentrations was addedto medium containing HCV JcR2a generated in culture (445.5 μL mediumcontaining virus was transferred to 8 eppendorfs, each of whichcontained 4.5 μL compound at various concentrations to achieve desiredfinal concentrations; i.e 50 μM, 25 μM etc) the 9th eppendorf, apositive control, contained DMSO solvent. A hepatitis C virus JcR2areporter construct was used. (A genotype 2, starin A, chemiric constructwhich has a Renilla luciferase gene fused in frame its open readingframe. Viral genome translation and replication is relative to Renillaluciferase expression).

The virus/compound preparation was then inoculated to the cells, induplicates, and incubated for 4 hours at 37° C. with 5% CO₂ supply.After 4 hours the medium containing virus/compound was aspirated fromthe cells following which cells were washed with sterile PBS, 200 μL perwell, to removal any residual virus or compound.

The cells were replenished with 200 μL/well DMEM and incubated for 48hours at 37° C. with 5% CO₂ supply. After 48 hours, the medium wasaspirated from the wells and then the cells were washed twice with 200μL PBS. Cells were then lysed with 1× passive lysis buffer and thelysate was analysed on a Berthold plate luminometer.

Virus entry into the cells was quantified by measuring Renillaluciferase expression. The read-outs from wells that were treated withcompounds were normalized to the read-out from wells that were treatedwith DMSO control. A decrease in Renilla luciferase expression, withstable expression of firefly luciferase, is relative to ability of thecompound to inhibit virus entry into the cells.

As can be seen from FIG. 20A, LabyA1 inhibits HCV virus entry with anIC50 of 1.05 μM and an 1090 of 9.163 μM. FIG. 20B shows that LabyA2inhibits HCV virus entry with an IC50 of 1.728 μM and an 1090 of 24.9μM. No cytotoxicity was observed at the tested LabyA1 and LabyA2concentrations.

EXAMPLE 9: CELL-BASED HIGH-THROUGHPUT SCREENING (HTS) SYSTEM

A cell-based screening system was used to determine the cytotoxicconcentration (CC50) of labyrinthopeptin A1 and A2.

1×10⁴ HEp-2 cells, which are stably expressing the reporter gene of afirefly luciferase (FF-luc), were seeded in a 96-well plate in 200 μlappropriate media. After 72 h of incubation at 37° C. in the presence ofincreasing concentrations of labyrinthopeptin A1 or A2 up to 100 μM, thecells have been lysed in 35 μl lysis buffer and the extinction of theFF-luc (RLU) was measured using a plate luminometer (Berthold). Thenumber of surviving cells is indirectly proportional to residualluciferase expression.

The half maximal cytotoxic concentration (CC50) has been calculated forlabyrinthopeptin A1 CC50=79.70 μM. There was no cytotoxic affect forlabyrinthopeptin A2 detectable up to a concentration of 100 μM.

EXAMPLE 10: SUMMARY OF ANTI-VIRAL EFFECTS OF LABYRINTHOPEPTINS

Table 4 shows the IC50 values of the anti-viral activities of LabyA1,LabyA2, the combination of LabyA1 and LabyA2 (LabyA1/A2), the LabyA1derivative “LabyA1-hexyn” (herein also called “LabyA1-Hexyn”), theLabyA2 derivative “LabyA2-hexyn” (herein also called “LabyA2-Hexyn”), aswell as the combination of LabyA1-hexyn and LabyA2-hexyn(LabyA1/A2-hexyn).

TABLE 4 IC50 values (in μM and μg/ml) of the anti-viral activity oflabyrinthopeptins, combinations of labyrinthopeptins andlabyrinthopeptin derivatives. LabyA1 LabyA2 LabyA1/A2 LabyA1-hexynLabyA2-hexyn LabyA1/A2 - hexyn μM μg/ml μM μg/ml μM μg/ml μM μg/ml μMμg/ml μM μg/ml DENV 1.78 3.7 8.00 15.4 1.30 2.6 1.70 3.7 7.03 14.2 0.962.0 RSV 0.39¹ 0.8¹ 4.97¹ 9.56¹ — — — — — — — — KSHV 2 4.2 15 28.9 — — —— — — — — TBEV 24.10 50 >25.99 >50 8.34 16.67 — — — — — — CMV 1.3 2.75.4 μM 10.4 — — — — — — — — CHIKV 0.5-1.7 1.0-3.5 — — — — — — — — — —VSV 1.1-3.7 2.3-7.7 — — — — — — — — — — ZIKV 2.22 4.6 2.81 5.4 1.75 3.5— — — — — — HCV 1.05 2.18 1.728 3.32 — — — — — — — — LabyA1 = LabyA2 =LabyA1-hexyn = LabyA2-hexyn = 2075.33 g/mol 1924.16 g/mol 2170.45 g/mol2019.28 g/mol ¹These values are measured by intracellular RSV-P staining(see FIG. 16C).

The present invention refers to the following amino acid sequences:

SEQ ID NO: 1: Amino acid sequence of the labyrinthopeptin of the presentinventionSEQ ID NO: 2: Amino acid sequence of the labyrinthopeptin derivative ofthe present inventionSEQ ID NO: 3: Amino acid sequence of LabyA1SEQ ID NO: 4: Amino acid sequence of LabyA2

SEQ ID NO: 5: RT-Primer 5′-GGTTTCCCAGCTTCTCCTGG-3′SEQ ID NO: 6: ZIKV-specific forward primer 5′-AAAAACCCCATGTGGAGAGG-3′SEQ ID NO: 7: ZIKV-specific reverse primer 5′-CATTCCTTCAGTGTGTCACC-3′

1. A peptide comprising the amino acid sequence

wherein Lab is labionin X₁ is an amino acid selected from Asn, Asp, andGlu; X₂ is an amino acid selected form Ala, Trp, and Ser; X₃ is an aminoacid selected from Val, Leu, and Ile; X₄ is an amino acid selected fromTrp and Tyr; X₅ is an amino acid selected from Glu and Asp; X₆ is anamino acid selected from Thr and Ser; X₇ is an amino acid selected fromGly and Pro; X₈ consists of a sequence of 3 to 5 amino acids; R₁ isselected from H, a (C₂-C₁₂)alkynyl, a C(O)—(C₂-C₁₂)alkynyl, aC(O)—O—(C₂-C₁₂)alkynyl, and a C(O)NH—(C₂-C₁₂)alkynyl; wherein R₁ carriesthe alkynyl group at the terminal position, and R₂ is selected from H, a[C(O)]—NH—(C₂-C₁₂)alkynyl or a [C(O)]—O—(C₂-C₁₂)alkynyl; wherein themoiety [C(O)] is the carbonyl group of the terminal amino acid; whereinR₂ carries the alkynyl group at the terminal position; wherein if R₁ isH, then R₂ is not H.
 2. The peptide of claim 1, wherein R₁ and/or R₂is/are derivatized with an azide-labeled compound.
 3. The peptide ofclaim 2, wherein said compound is a compound selected from an anti-viraldrug or a marker molecule.
 4. (canceled)
 5. A pharmaceutical compositioncomprising the peptide of claim 1, and a pharmaceutically acceptablecarrier and/or diluent.
 6. A method of treating and/or preventing aninfection in a subject, wherein the method comprises administering aneffective dose of the peptide of claim
 1. 7. The method of claim 6,wherein said infection is an infection with any one of the virusesselected from human respiratory syncytial virus (RSV), Kaposisarcoma-associated herpesvirus (KSHV), cytomegalovirus (CMV), denguevirus (DENV), chikungunya virus (CHIKV), tick-borne encephalitis virus(TBEV; FSME virus), vesicular stomatitis Indiana virus (VSV) zika virus(ZIKV) and hepatitis C virus (HCV).
 8. The method of claim 11, whereinsaid infection is an infection with any one of the viruses selected fromRSV, KSHV, CMV, DENV, CHIKV, TBEV, VSV, ZIKV and HCV.
 9. A peptidecomprising the amino acid sequence

wherein Lab is labionin X₁ is an amino acid selected from Asn, Asp, andGlu; X₂ is an amino acid selected form Ala, Trp, and Ser; X₃ is an aminoacid selected from Val, Leu, and Ile; X₄ is an amino acid selected fromTrp and Tyr; X₅ is an amino acid selected from Glu and Asp; X₆ is anamino acid selected from Thr and Ser; X₇ is an amino acid selected fromGly and Pro; and X₈ consists of a sequence of 3 to 5 amino acids.
 10. Apharmaceutical composition comprising the peptide of claim 9, and apharmaceutically acceptable carrier and/or diluent.
 11. A method oftreating and/or preventing an infection in a subject, wherein the methodcomprises administering an effective dose of the peptide as defined inclaim 9 to a subject in need of such a treatment.
 12. The peptide ofclaim 1, wherein said peptide has a length of maximal 30 amino acids.13. The peptide of claim 1, wherein X₁ is Asn or Asp; X₂ is Ala or Trp;X₃ is Val or Leu; X₄ is Trp; X₅ is Glu; X₆ is Thr; X₇ is Gly; and X₈ isan amino acid sequence consisting of the amino acid sequenceTrp-Val-Pro-Phe-dehydrobutyrine, the amino acid sequence Leu-Phe-Ala.14. The peptide of claim 1, wherein X₁ is Asn; X₂ is Ala; X₃ is Val; X₄is Trp; X₅ is Glu; X₆ is Thr; X₇ is Gly; and X₈ is an amino acidsequence consisting of the amino acid sequenceTrp-Val-Pro-Phe-dehydrobutyrine.
 15. The peptide of claim 1, wherein X₁is Asp; X₂ is Trp; X₃ is Leu; X₄ is Trp; X₅ is Glu; X₆ is Thr; X₇ isGly; and X₈ is an amino acid sequence consisting of the amino acidsequence Leu-Phe-Ala.
 16. A composition comprising the peptide asdefined in claim 14 and the peptide as defined in claim
 15. 17. Thecomposition as defined in claim 16, wherein the composition furthercomprises a pharmaceutically acceptable carrier and/or diluent.
 18. Amethod of treating and/or preventing an infection in a subject, whereinthe method comprises administering an effective dose of thepharmaceutical composition as defined in claim 17 to a subject in needthereof.
 19. The method of claim 18, wherein the infection is aninfection with any one of the viruses selected from RSV, KSHV, CMV,DENV, CHIKV, TBEV, VSV, ZIKV and HCV.
 20. (canceled)
 21. The method ofclaim 6, wherein the method further comprises co-administration with atleast one other active agent.
 22. The method of claim 21, wherein theother active agent is a CMV inhibitor, a KSHV inhibitor, a RSVinhibitor, a DENV inhibitor, a CHIKV inhibitor, a TBEV inhibitor, a VSVinhibitor, a ZIKV inhibitor, or a HCV inhibitor.
 23. The method of claim6, wherein the peptide is administered orally, intravenously,subcutaneously or intramuscularly.
 24. The method of claim, wherein thevirus is CMV.
 25. The method of claim 8, wherein the virus is DENV.